diff --git a/api/cmd/portainer/main.go b/api/cmd/portainer/main.go
index 47acddedb..2886468f8 100644
--- a/api/cmd/portainer/main.go
+++ b/api/cmd/portainer/main.go
@@ -506,7 +506,7 @@ func buildServer(flags *portainer.CLIFlags) portainer.Server {
 
 	adminPasswordHash := ""
 	if *flags.AdminPasswordFile != "" {
-		content, err := fileService.GetFileContent(*flags.AdminPasswordFile)
+		content, err := fileService.GetFileContent(*flags.AdminPasswordFile, "")
 		if err != nil {
 			log.Fatalf("failed getting admin password file: %v", err)
 		}
diff --git a/api/exec/compose_stack.go b/api/exec/compose_stack.go
index 3bdb43430..4c9da2f72 100644
--- a/api/exec/compose_stack.go
+++ b/api/exec/compose_stack.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"os"
 	"path"
-	"path/filepath"
 	"strings"
 
 	"github.com/pkg/errors"
@@ -16,6 +15,7 @@ import (
 	portainer "github.com/portainer/portainer/api"
 	"github.com/portainer/portainer/api/http/proxy"
 	"github.com/portainer/portainer/api/http/proxy/factory"
+	"github.com/portainer/portainer/api/internal/stackutils"
 )
 
 // ComposeStackManager is a wrapper for docker-compose binary
@@ -58,7 +58,7 @@ func (manager *ComposeStackManager) Up(ctx context.Context, stack *portainer.Sta
 		return errors.Wrap(err, "failed to create env file")
 	}
 
-	filePaths := getStackFiles(stack)
+	filePaths := stackutils.GetStackFilePaths(stack)
 	err = manager.deployer.Deploy(ctx, stack.ProjectPath, url, stack.Name, filePaths, envFilePath)
 	return errors.Wrap(err, "failed to deploy a stack")
 }
@@ -73,7 +73,7 @@ func (manager *ComposeStackManager) Down(ctx context.Context, stack *portainer.S
 		defer proxy.Close()
 	}
 
-	filePaths := getStackFiles(stack)
+	filePaths := stackutils.GetStackFilePaths(stack)
 	err = manager.deployer.Remove(ctx, stack.ProjectPath, url, stack.Name, filePaths)
 	return errors.Wrap(err, "failed to remove a stack")
 }
@@ -115,27 +115,3 @@ func createEnvFile(stack *portainer.Stack) (string, error) {
 
 	return "stack.env", nil
 }
-
-// getStackFiles returns list of stack's confile file paths.
-// items in the list would be sanitized according to following criterias:
-// 1. no empty paths
-// 2. no "../xxx" paths that are trying to escape stack folder
-// 3. no dir paths
-// 4. root paths would be made relative
-func getStackFiles(stack *portainer.Stack) []string {
-	paths := make([]string, 0, len(stack.AdditionalFiles)+1)
-
-	for _, p := range append([]string{stack.EntryPoint}, stack.AdditionalFiles...) {
-		if strings.HasPrefix(p, "/") {
-			p = `.` + p
-		}
-
-		if p == `` || p == `.` || strings.HasPrefix(p, `..`) || strings.HasSuffix(p, string(filepath.Separator)) {
-			continue
-		}
-
-		paths = append(paths, p)
-	}
-
-	return paths
-}
diff --git a/api/exec/compose_stack_test.go b/api/exec/compose_stack_test.go
index 0b5dec2a3..c61285ebd 100644
--- a/api/exec/compose_stack_test.go
+++ b/api/exec/compose_stack_test.go
@@ -64,21 +64,3 @@ func Test_createEnvFile(t *testing.T) {
 		})
 	}
 }
-
-func Test_getStackFiles(t *testing.T) {
-	stack := &portainer.Stack{
-		EntryPoint: "./file", // picks entry point
-		AdditionalFiles: []string{
-			``,                  // ignores empty string
-			`.`,                 // ignores .
-			`..`,                // ignores ..
-			`./dir/`,            // ignrores paths that end with trailing /
-			`/with-root-prefix`, // replaces "root" based paths with relative
-			`./relative`,        // keeps relative paths
-			`../escape`,         // prevents dir escape
-		},
-	}
-
-	filePaths := getStackFiles(stack)
-	assert.ElementsMatch(t, filePaths, []string{`./file`, `./with-root-prefix`, `./relative`})
-}
diff --git a/api/exec/swarm_stack.go b/api/exec/swarm_stack.go
index 21a34a722..6872d2555 100644
--- a/api/exec/swarm_stack.go
+++ b/api/exec/swarm_stack.go
@@ -191,7 +191,7 @@ func (manager *SwarmStackManager) updateDockerCLIConfiguration(configPath string
 func (manager *SwarmStackManager) retrieveConfigurationFromDisk(path string) (map[string]interface{}, error) {
 	var config map[string]interface{}
 
-	raw, err := manager.fileService.GetFileContent(path)
+	raw, err := manager.fileService.GetFileContent(path, "")
 	if err != nil {
 		return make(map[string]interface{}), nil
 	}
diff --git a/api/filesystem/filesystem.go b/api/filesystem/filesystem.go
index 3f68bcf53..b76d337f3 100644
--- a/api/filesystem/filesystem.go
+++ b/api/filesystem/filesystem.go
@@ -6,14 +6,14 @@ import (
 	"encoding/pem"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"path/filepath"
+	"strings"
 
 	"github.com/gofrs/uuid"
 	portainer "github.com/portainer/portainer/api"
 
 	"io"
 	"os"
-	"path"
 )
 
 const (
@@ -69,12 +69,31 @@ type Service struct {
 	fileStorePath string
 }
 
+// JoinPaths takes a trusted root path and a list of untrusted paths and joins
+// them together using directory separators while enforcing that the untrusted
+// paths cannot go higher up than the trusted root
+func JoinPaths(trustedRoot string, untrustedPaths ...string) string {
+	if trustedRoot == "" {
+		trustedRoot = "."
+	}
+
+	p := filepath.Join(trustedRoot, filepath.Join(append([]string{"/"}, untrustedPaths...)...))
+
+	// avoid setting a volume name from the untrusted paths
+	vnp := filepath.VolumeName(p)
+	if filepath.VolumeName(trustedRoot) == "" && vnp != "" {
+		return strings.TrimPrefix(strings.TrimPrefix(p, vnp), `\`)
+	}
+
+	return p
+}
+
 // NewService initializes a new service. It creates a data directory and a directory to store files
 // inside this directory if they don't exist.
 func NewService(dataStorePath, fileStorePath string) (*Service, error) {
 	service := &Service{
 		dataStorePath: dataStorePath,
-		fileStorePath: path.Join(dataStorePath, fileStorePath),
+		fileStorePath: JoinPaths(dataStorePath, fileStorePath),
 	}
 
 	err := os.MkdirAll(dataStorePath, 0755)
@@ -112,12 +131,12 @@ func NewService(dataStorePath, fileStorePath string) (*Service, error) {
 
 // GetBinaryFolder returns the full path to the binary store on the filesystem
 func (service *Service) GetBinaryFolder() string {
-	return path.Join(service.fileStorePath, BinaryStorePath)
+	return JoinPaths(service.fileStorePath, BinaryStorePath)
 }
 
 // GetDockerConfigPath returns the full path to the docker config store on the filesystem
 func (service *Service) GetDockerConfigPath() string {
-	return path.Join(service.fileStorePath, DockerConfigPath)
+	return JoinPaths(service.fileStorePath, DockerConfigPath)
 }
 
 // RemoveDirectory removes a directory on the filesystem.
@@ -128,7 +147,7 @@ func (service *Service) RemoveDirectory(directoryPath string) error {
 // GetStackProjectPath returns the absolute path on the FS for a stack based
 // on its identifier.
 func (service *Service) GetStackProjectPath(stackIdentifier string) string {
-	return path.Join(service.fileStorePath, ComposeStorePath, stackIdentifier)
+	return JoinPaths(service.wrapFileStore(ComposeStorePath), stackIdentifier)
 }
 
 // Copy copies the file on fromFilePath to toFilePath
@@ -194,13 +213,13 @@ func (service *Service) Copy(fromFilePath string, toFilePath string, deleteIfExi
 // StoreStackFileFromBytes creates a subfolder in the ComposeStorePath and stores a new file from bytes.
 // It returns the path to the folder where the file is stored.
 func (service *Service) StoreStackFileFromBytes(stackIdentifier, fileName string, data []byte) (string, error) {
-	stackStorePath := path.Join(ComposeStorePath, stackIdentifier)
+	stackStorePath := JoinPaths(ComposeStorePath, stackIdentifier)
 	err := service.createDirectoryInStore(stackStorePath)
 	if err != nil {
 		return "", err
 	}
 
-	composeFilePath := path.Join(stackStorePath, fileName)
+	composeFilePath := JoinPaths(stackStorePath, fileName)
 	r := bytes.NewReader(data)
 
 	err = service.createFileInStore(composeFilePath, r)
@@ -208,25 +227,25 @@ func (service *Service) StoreStackFileFromBytes(stackIdentifier, fileName string
 		return "", err
 	}
 
-	return path.Join(service.fileStorePath, stackStorePath), nil
+	return service.wrapFileStore(stackStorePath), nil
 }
 
 // GetEdgeStackProjectPath returns the absolute path on the FS for a edge stack based
 // on its identifier.
 func (service *Service) GetEdgeStackProjectPath(edgeStackIdentifier string) string {
-	return path.Join(service.fileStorePath, EdgeStackStorePath, edgeStackIdentifier)
+	return JoinPaths(service.wrapFileStore(EdgeStackStorePath), edgeStackIdentifier)
 }
 
 // StoreEdgeStackFileFromBytes creates a subfolder in the EdgeStackStorePath and stores a new file from bytes.
 // It returns the path to the folder where the file is stored.
 func (service *Service) StoreEdgeStackFileFromBytes(edgeStackIdentifier, fileName string, data []byte) (string, error) {
-	stackStorePath := path.Join(EdgeStackStorePath, edgeStackIdentifier)
+	stackStorePath := JoinPaths(EdgeStackStorePath, edgeStackIdentifier)
 	err := service.createDirectoryInStore(stackStorePath)
 	if err != nil {
 		return "", err
 	}
 
-	composeFilePath := path.Join(stackStorePath, fileName)
+	composeFilePath := JoinPaths(stackStorePath, fileName)
 	r := bytes.NewReader(data)
 
 	err = service.createFileInStore(composeFilePath, r)
@@ -234,20 +253,20 @@ func (service *Service) StoreEdgeStackFileFromBytes(edgeStackIdentifier, fileNam
 		return "", err
 	}
 
-	return path.Join(service.fileStorePath, stackStorePath), nil
+	return service.wrapFileStore(stackStorePath), nil
 }
 
 // StoreRegistryManagementFileFromBytes creates a subfolder in the
 // ExtensionRegistryManagementStorePath and stores a new file from bytes.
 // It returns the path to the folder where the file is stored.
 func (service *Service) StoreRegistryManagementFileFromBytes(folder, fileName string, data []byte) (string, error) {
-	extensionStorePath := path.Join(ExtensionRegistryManagementStorePath, folder)
+	extensionStorePath := JoinPaths(ExtensionRegistryManagementStorePath, folder)
 	err := service.createDirectoryInStore(extensionStorePath)
 	if err != nil {
 		return "", err
 	}
 
-	file := path.Join(extensionStorePath, fileName)
+	file := JoinPaths(extensionStorePath, fileName)
 	r := bytes.NewReader(data)
 
 	err = service.createFileInStore(file, r)
@@ -255,13 +274,13 @@ func (service *Service) StoreRegistryManagementFileFromBytes(folder, fileName st
 		return "", err
 	}
 
-	return path.Join(service.fileStorePath, file), nil
+	return service.wrapFileStore(file), nil
 }
 
 // StoreTLSFileFromBytes creates a folder in the TLSStorePath and stores a new file from bytes.
 // It returns the path to the newly created file.
 func (service *Service) StoreTLSFileFromBytes(folder string, fileType portainer.TLSFileType, data []byte) (string, error) {
-	storePath := path.Join(TLSStorePath, folder)
+	storePath := JoinPaths(TLSStorePath, folder)
 	err := service.createDirectoryInStore(storePath)
 	if err != nil {
 		return "", err
@@ -279,13 +298,13 @@ func (service *Service) StoreTLSFileFromBytes(folder string, fileType portainer.
 		return "", ErrUndefinedTLSFileType
 	}
 
-	tlsFilePath := path.Join(storePath, fileName)
+	tlsFilePath := JoinPaths(storePath, fileName)
 	r := bytes.NewReader(data)
 	err = service.createFileInStore(tlsFilePath, r)
 	if err != nil {
 		return "", err
 	}
-	return path.Join(service.fileStorePath, tlsFilePath), nil
+	return service.wrapFileStore(tlsFilePath), nil
 }
 
 // GetPathForTLSFile returns the absolute path to a specific TLS file for an environment(endpoint).
@@ -301,17 +320,13 @@ func (service *Service) GetPathForTLSFile(folder string, fileType portainer.TLSF
 	default:
 		return "", ErrUndefinedTLSFileType
 	}
-	return path.Join(service.fileStorePath, TLSStorePath, folder, fileName), nil
+	return JoinPaths(service.wrapFileStore(TLSStorePath), folder, fileName), nil
 }
 
 // DeleteTLSFiles deletes a folder in the TLS store path.
 func (service *Service) DeleteTLSFiles(folder string) error {
-	storePath := path.Join(service.fileStorePath, TLSStorePath, folder)
-	err := os.RemoveAll(storePath)
-	if err != nil {
-		return err
-	}
-	return nil
+	storePath := JoinPaths(service.wrapFileStore(TLSStorePath), folder)
+	return os.RemoveAll(storePath)
 }
 
 // DeleteTLSFile deletes a specific TLS file from a folder.
@@ -328,20 +343,19 @@ func (service *Service) DeleteTLSFile(folder string, fileType portainer.TLSFileT
 		return ErrUndefinedTLSFileType
 	}
 
-	filePath := path.Join(service.fileStorePath, TLSStorePath, folder, fileName)
+	filePath := JoinPaths(service.wrapFileStore(TLSStorePath), folder, fileName)
 
-	err := os.Remove(filePath)
-	if err != nil {
-		return err
-	}
-	return nil
+	return os.Remove(filePath)
 }
 
 // GetFileContent returns the content of a file as bytes.
-func (service *Service) GetFileContent(filePath string) ([]byte, error) {
-	content, err := ioutil.ReadFile(filePath)
+func (service *Service) GetFileContent(trustedRoot, filePath string) ([]byte, error) {
+	content, err := os.ReadFile(JoinPaths(trustedRoot, filePath))
 	if err != nil {
-		return nil, err
+		if filePath == "" {
+			filePath = trustedRoot
+		}
+		return nil, fmt.Errorf("could not get the contents of the file '%s'", filePath)
 	}
 
 	return content, nil
@@ -359,7 +373,7 @@ func (service *Service) WriteJSONToFile(path string, content interface{}) error
 		return err
 	}
 
-	return ioutil.WriteFile(path, jsonContent, 0644)
+	return os.WriteFile(path, jsonContent, 0644)
 }
 
 // FileExists checks for the existence of the specified file.
@@ -369,23 +383,17 @@ func (service *Service) FileExists(filePath string) (bool, error) {
 
 // KeyPairFilesExist checks for the existence of the key files.
 func (service *Service) KeyPairFilesExist() (bool, error) {
-	privateKeyPath := path.Join(service.dataStorePath, PrivateKeyFile)
+	privateKeyPath := JoinPaths(service.dataStorePath, PrivateKeyFile)
 	exists, err := service.FileExists(privateKeyPath)
-	if err != nil {
+	if err != nil || !exists {
 		return false, err
 	}
-	if !exists {
-		return false, nil
-	}
 
-	publicKeyPath := path.Join(service.dataStorePath, PublicKeyFile)
+	publicKeyPath := JoinPaths(service.dataStorePath, PublicKeyFile)
 	exists, err = service.FileExists(publicKeyPath)
-	if err != nil {
+	if err != nil || !exists {
 		return false, err
 	}
-	if !exists {
-		return false, nil
-	}
 
 	return true, nil
 }
@@ -397,12 +405,7 @@ func (service *Service) StoreKeyPair(private, public []byte, privatePEMHeader, p
 		return err
 	}
 
-	err = service.createPEMFileInStore(public, publicPEMHeader, PublicKeyFile)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return service.createPEMFileInStore(public, publicPEMHeader, PublicKeyFile)
 }
 
 // LoadKeyPair retrieve the content of both key files on disk.
@@ -422,13 +425,13 @@ func (service *Service) LoadKeyPair() ([]byte, []byte, error) {
 
 // createDirectoryInStore creates a new directory in the file store
 func (service *Service) createDirectoryInStore(name string) error {
-	path := path.Join(service.fileStorePath, name)
+	path := service.wrapFileStore(name)
 	return os.MkdirAll(path, 0700)
 }
 
 // createFile creates a new file in the file store with the content from r.
 func (service *Service) createFileInStore(filePath string, r io.Reader) error {
-	path := path.Join(service.fileStorePath, filePath)
+	path := service.wrapFileStore(filePath)
 
 	out, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
@@ -437,15 +440,11 @@ func (service *Service) createFileInStore(filePath string, r io.Reader) error {
 	defer out.Close()
 
 	_, err = io.Copy(out, r)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return err
 }
 
 func (service *Service) createPEMFileInStore(content []byte, fileType, filePath string) error {
-	path := path.Join(service.fileStorePath, filePath)
+	path := service.wrapFileStore(filePath)
 	block := &pem.Block{Type: fileType, Bytes: content}
 
 	out, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
@@ -454,18 +453,13 @@ func (service *Service) createPEMFileInStore(content []byte, fileType, filePath
 	}
 	defer out.Close()
 
-	err = pem.Encode(out, block)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return pem.Encode(out, block)
 }
 
 func (service *Service) getContentFromPEMFile(filePath string) ([]byte, error) {
-	path := path.Join(service.fileStorePath, filePath)
+	path := service.wrapFileStore(filePath)
 
-	fileContent, err := ioutil.ReadFile(path)
+	fileContent, err := os.ReadFile(path)
 	if err != nil {
 		return nil, err
 	}
@@ -477,19 +471,19 @@ func (service *Service) getContentFromPEMFile(filePath string) ([]byte, error) {
 // GetCustomTemplateProjectPath returns the absolute path on the FS for a custom template based
 // on its identifier.
 func (service *Service) GetCustomTemplateProjectPath(identifier string) string {
-	return path.Join(service.fileStorePath, CustomTemplateStorePath, identifier)
+	return JoinPaths(service.wrapFileStore(CustomTemplateStorePath), identifier)
 }
 
 // StoreCustomTemplateFileFromBytes creates a subfolder in the CustomTemplateStorePath and stores a new file from bytes.
 // It returns the path to the folder where the file is stored.
 func (service *Service) StoreCustomTemplateFileFromBytes(identifier, fileName string, data []byte) (string, error) {
-	customTemplateStorePath := path.Join(CustomTemplateStorePath, identifier)
+	customTemplateStorePath := JoinPaths(CustomTemplateStorePath, identifier)
 	err := service.createDirectoryInStore(customTemplateStorePath)
 	if err != nil {
 		return "", err
 	}
 
-	templateFilePath := path.Join(customTemplateStorePath, fileName)
+	templateFilePath := JoinPaths(customTemplateStorePath, fileName)
 	r := bytes.NewReader(data)
 
 	err = service.createFileInStore(templateFilePath, r)
@@ -497,32 +491,32 @@ func (service *Service) StoreCustomTemplateFileFromBytes(identifier, fileName st
 		return "", err
 	}
 
-	return path.Join(service.fileStorePath, customTemplateStorePath), nil
+	return service.wrapFileStore(customTemplateStorePath), nil
 }
 
 // GetEdgeJobFolder returns the absolute path on the filesystem for an Edge job based
 // on its identifier.
 func (service *Service) GetEdgeJobFolder(identifier string) string {
-	return path.Join(service.fileStorePath, EdgeJobStorePath, identifier)
+	return JoinPaths(service.wrapFileStore(EdgeJobStorePath), identifier)
 }
 
 // StoreEdgeJobFileFromBytes creates a subfolder in the EdgeJobStorePath and stores a new file from bytes.
 // It returns the path to the folder where the file is stored.
 func (service *Service) StoreEdgeJobFileFromBytes(identifier string, data []byte) (string, error) {
-	edgeJobStorePath := path.Join(EdgeJobStorePath, identifier)
+	edgeJobStorePath := JoinPaths(EdgeJobStorePath, identifier)
 	err := service.createDirectoryInStore(edgeJobStorePath)
 	if err != nil {
 		return "", err
 	}
 
-	filePath := path.Join(edgeJobStorePath, createEdgeJobFileName(identifier))
+	filePath := JoinPaths(edgeJobStorePath, createEdgeJobFileName(identifier))
 	r := bytes.NewReader(data)
 	err = service.createFileInStore(filePath, r)
 	if err != nil {
 		return "", err
 	}
 
-	return path.Join(service.fileStorePath, filePath), nil
+	return service.wrapFileStore(filePath), nil
 }
 
 func createEdgeJobFileName(identifier string) string {
@@ -532,20 +526,14 @@ func createEdgeJobFileName(identifier string) string {
 // ClearEdgeJobTaskLogs clears the Edge job task logs
 func (service *Service) ClearEdgeJobTaskLogs(edgeJobID string, taskID string) error {
 	path := service.getEdgeJobTaskLogPath(edgeJobID, taskID)
-
-	err := os.Remove(path)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return os.Remove(path)
 }
 
 // GetEdgeJobTaskLogFileContent fetches the Edge job task logs
 func (service *Service) GetEdgeJobTaskLogFileContent(edgeJobID string, taskID string) (string, error) {
 	path := service.getEdgeJobTaskLogPath(edgeJobID, taskID)
 
-	fileContent, err := ioutil.ReadFile(path)
+	fileContent, err := os.ReadFile(path)
 	if err != nil {
 		return "", err
 	}
@@ -555,20 +543,15 @@ func (service *Service) GetEdgeJobTaskLogFileContent(edgeJobID string, taskID st
 
 // StoreEdgeJobTaskLogFileFromBytes stores the log file
 func (service *Service) StoreEdgeJobTaskLogFileFromBytes(edgeJobID, taskID string, data []byte) error {
-	edgeJobStorePath := path.Join(EdgeJobStorePath, edgeJobID)
+	edgeJobStorePath := JoinPaths(EdgeJobStorePath, edgeJobID)
 	err := service.createDirectoryInStore(edgeJobStorePath)
 	if err != nil {
 		return err
 	}
 
-	filePath := path.Join(edgeJobStorePath, fmt.Sprintf("logs_%s", taskID))
+	filePath := JoinPaths(edgeJobStorePath, fmt.Sprintf("logs_%s", taskID))
 	r := bytes.NewReader(data)
-	err = service.createFileInStore(filePath, r)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return service.createFileInStore(filePath, r)
 }
 
 func (service *Service) getEdgeJobTaskLogPath(edgeJobID string, taskID string) string {
@@ -582,7 +565,7 @@ func (service *Service) GetTemporaryPath() (string, error) {
 		return "", err
 	}
 
-	return path.Join(service.fileStorePath, TempPath, uid.String()), nil
+	return JoinPaths(service.wrapFileStore(TempPath), uid.String()), nil
 }
 
 // GetDataStorePath returns path to data folder
@@ -591,12 +574,12 @@ func (service *Service) GetDatastorePath() string {
 }
 
 func (service *Service) wrapFileStore(filepath string) string {
-	return path.Join(service.fileStorePath, filepath)
+	return JoinPaths(service.fileStorePath, filepath)
 }
 
 func defaultCertPathUnderFileStore() (string, string) {
-	certPath := path.Join(SSLCertPath, DefaultSSLCertFilename)
-	keyPath := path.Join(SSLCertPath, DefaultSSLKeyFilename)
+	certPath := JoinPaths(SSLCertPath, DefaultSSLCertFilename)
+	keyPath := JoinPaths(SSLCertPath, DefaultSSLKeyFilename)
 	return certPath, keyPath
 }
 
diff --git a/api/filesystem/filesystem_linux_test.go b/api/filesystem/filesystem_linux_test.go
new file mode 100644
index 000000000..dad55c951
--- /dev/null
+++ b/api/filesystem/filesystem_linux_test.go
@@ -0,0 +1,70 @@
+package filesystem
+
+import "testing"
+
+func TestJoinPaths(t *testing.T) {
+	var ts = []struct {
+		trusted   string
+		untrusted string
+		expected  string
+	}{
+		{"", "", "."},
+		{"", ".", "."},
+		{"", "d/e/f", "d/e/f"},
+		{"", "./d/e/f", "d/e/f"},
+		{"", "../d/e/f", "d/e/f"},
+		{"", "/d/e/f", "d/e/f"},
+		{"", "../../../etc/shadow", "etc/shadow"},
+
+		{".", "", "."},
+		{".", ".", "."},
+		{".", "d/e/f", "d/e/f"},
+		{".", "./d/e/f", "d/e/f"},
+		{".", "../d/e/f", "d/e/f"},
+		{".", "/d/e/f", "d/e/f"},
+		{".", "../../../etc/shadow", "etc/shadow"},
+
+		{"./", "", "."},
+		{"./", ".", "."},
+		{"./", "d/e/f", "d/e/f"},
+		{"./", "./d/e/f", "d/e/f"},
+		{"./", "../d/e/f", "d/e/f"},
+		{"./", "/d/e/f", "d/e/f"},
+		{"./", "../../../etc/shadow", "etc/shadow"},
+
+		{"a/b/c", "", "a/b/c"},
+		{"a/b/c", ".", "a/b/c"},
+		{"a/b/c", "d/e/f", "a/b/c/d/e/f"},
+		{"a/b/c", "./d/e/f", "a/b/c/d/e/f"},
+		{"a/b/c", "../d/e/f", "a/b/c/d/e/f"},
+		{"a/b/c", "../../../etc/shadow", "a/b/c/etc/shadow"},
+
+		{"/a/b/c", "", "/a/b/c"},
+		{"/a/b/c", ".", "/a/b/c"},
+		{"/a/b/c", "d/e/f", "/a/b/c/d/e/f"},
+		{"/a/b/c", "./d/e/f", "/a/b/c/d/e/f"},
+		{"/a/b/c", "../d/e/f", "/a/b/c/d/e/f"},
+		{"/a/b/c", "../../../etc/shadow", "/a/b/c/etc/shadow"},
+
+		{"./a/b/c", "", "a/b/c"},
+		{"./a/b/c", ".", "a/b/c"},
+		{"./a/b/c", "d/e/f", "a/b/c/d/e/f"},
+		{"./a/b/c", "./d/e/f", "a/b/c/d/e/f"},
+		{"./a/b/c", "../d/e/f", "a/b/c/d/e/f"},
+		{"./a/b/c", "../../../etc/shadow", "a/b/c/etc/shadow"},
+
+		{"../a/b/c", "", "../a/b/c"},
+		{"../a/b/c", ".", "../a/b/c"},
+		{"../a/b/c", "d/e/f", "../a/b/c/d/e/f"},
+		{"../a/b/c", "./d/e/f", "../a/b/c/d/e/f"},
+		{"../a/b/c", "../d/e/f", "../a/b/c/d/e/f"},
+		{"../a/b/c", "../../../etc/shadow", "../a/b/c/etc/shadow"},
+	}
+
+	for _, c := range ts {
+		r := JoinPaths(c.trusted, c.untrusted)
+		if r != c.expected {
+			t.Fatalf("expected '%s', got '%s'. Inputs = '%s', '%s'", c.expected, r, c.trusted, c.untrusted)
+		}
+	}
+}
diff --git a/api/filesystem/filesystem_windows_test.go b/api/filesystem/filesystem_windows_test.go
new file mode 100644
index 000000000..70187dd59
--- /dev/null
+++ b/api/filesystem/filesystem_windows_test.go
@@ -0,0 +1,120 @@
+package filesystem
+
+import "testing"
+
+func TestJoinPaths(t *testing.T) {
+	var ts = []struct {
+		trusted   string
+		untrusted string
+		expected  string
+	}{
+		{"", "", "."},
+		{"", ".", "."},
+		{"", "d/e/f", `d\e\f`},
+		{"", "./d/e/f", `d\e\f`},
+		{"", "../d/e/f", `d\e\f`},
+		{"", "/d/e/f", `d\e\f`},
+		{"", "../../../windows/system.ini", `windows\system.ini`},
+		{"", `C:\windows\system.ini`, `windows\system.ini`},
+		{"", `..\..\..\..\C:\windows\system.ini`, `windows\system.ini`},
+		{"", `\\server\a\b\c`, `server\a\b\c`},
+		{"", `..\..\..\..\\server\a\b\c`, `server\a\b\c`},
+
+		{".", "", "."},
+		{".", ".", "."},
+		{".", "d/e/f", `d\e\f`},
+		{".", "./d/e/f", `d\e\f`},
+		{".", "../d/e/f", `d\e\f`},
+		{".", "/d/e/f", `d\e\f`},
+		{".", "../../../windows/system.ini", `windows\system.ini`},
+		{".", `C:\windows\system.ini`, `windows\system.ini`},
+		{".", `..\..\..\..\C:\windows\system.ini`, `windows\system.ini`},
+		{".", `\\server\a\b\c`, `server\a\b\c`},
+		{".", `..\..\..\..\\server\a\b\c`, `server\a\b\c`},
+
+		{"./", "", "."},
+		{"./", ".", "."},
+		{"./", "d/e/f", `d\e\f`},
+		{"./", "./d/e/f", `d\e\f`},
+		{"./", "../d/e/f", `d\e\f`},
+		{"./", "/d/e/f", `d\e\f`},
+		{"./", "../../../windows/system.ini", `windows\system.ini`},
+		{"./", `C:\windows\system.ini`, `windows\system.ini`},
+		{"./", `..\..\..\..\C:\windows\system.ini`, `windows\system.ini`},
+		{"./", `\\server\a\b\c`, `server\a\b\c`},
+		{"./", `..\..\..\..\\server\a\b\c`, `server\a\b\c`},
+
+		{"a/b/c", "", `a\b\c`},
+		{"a/b/c", ".", `a\b\c`},
+		{"a/b/c", "d/e/f", `a\b\c\d\e\f`},
+		{"a/b/c", "./d/e/f", `a\b\c\d\e\f`},
+		{"a/b/c", "../d/e/f", `a\b\c\d\e\f`},
+		{"a/b/c", "../../../windows/system.ini", `a\b\c\windows\system.ini`},
+		{"a/b/c", `C:\windows\system.ini`, `a\b\c\C:\windows\system.ini`},
+		{"a/b/c", `..\..\..\..\C:\windows\system.ini`, `a\b\c\C:\windows\system.ini`},
+		{"a/b/c", `\\server\a\b\c`, `a\b\c\server\a\b\c`},
+		{"a/b/c", `..\..\..\..\\server\a\b\c`, `a\b\c\server\a\b\c`},
+
+		{"/a/b/c", "", `\a\b\c`},
+		{"/a/b/c", ".", `\a\b\c`},
+		{"/a/b/c", "d/e/f", `\a\b\c\d\e\f`},
+		{"/a/b/c", "./d/e/f", `\a\b\c\d\e\f`},
+		{"/a/b/c", "../d/e/f", `\a\b\c\d\e\f`},
+		{"/a/b/c", "../../../windows/system.ini", `\a\b\c\windows\system.ini`},
+		{"/a/b/c", `C:\windows\system.ini`, `\a\b\c\C:\windows\system.ini`},
+		{"/a/b/c", `..\..\..\..\C:\windows\system.ini`, `\a\b\c\C:\windows\system.ini`},
+		{"/a/b/c", `\\server\a\b\c`, `\a\b\c\server\a\b\c`},
+		{"/a/b/c", `..\..\..\..\\server\a\b\c`, `\a\b\c\server\a\b\c`},
+
+		{"./a/b/c", "", `a\b\c`},
+		{"./a/b/c", ".", `a\b\c`},
+		{"./a/b/c", "d/e/f", `a\b\c\d\e\f`},
+		{"./a/b/c", "./d/e/f", `a\b\c\d\e\f`},
+		{"./a/b/c", "../d/e/f", `a\b\c\d\e\f`},
+		{"./a/b/c", "../../../windows/system.ini", `a\b\c\windows\system.ini`},
+		{"./a/b/c", `C:\windows\system.ini`, `a\b\c\C:\windows\system.ini`},
+		{"./a/b/c", `..\..\..\..\C:\windows\system.ini`, `a\b\c\C:\windows\system.ini`},
+		{"./a/b/c", `\\server\a\b\c`, `a\b\c\server\a\b\c`},
+		{"./a/b/c", `..\..\..\..\\server\a\b\c`, `a\b\c\server\a\b\c`},
+
+		{"../a/b/c", "", `..\a\b\c`},
+		{"../a/b/c", ".", `..\a\b\c`},
+		{"../a/b/c", "d/e/f", `..\a\b\c\d\e\f`},
+		{"../a/b/c", "./d/e/f", `..\a\b\c\d\e\f`},
+		{"../a/b/c", "../d/e/f", `..\a\b\c\d\e\f`},
+		{"../a/b/c", "../../../windows/system.ini", `..\a\b\c\windows\system.ini`},
+		{"../a/b/c", `C:\windows\system.ini`, `..\a\b\c\C:\windows\system.ini`},
+		{"../a/b/c", `..\..\..\..\C:\windows\system.ini`, `..\a\b\c\C:\windows\system.ini`},
+		{"../a/b/c", `\\server\a\b\c`, `..\a\b\c\server\a\b\c`},
+		{"../a/b/c", `..\..\..\..\\server\a\b\c`, `..\a\b\c\server\a\b\c`},
+
+		{"C:/a/b/c", "", `C:\a\b\c`},
+		{"C:/a/b/c", ".", `C:\a\b\c`},
+		{"C:/a/b/c", "d/e/f", `C:\a\b\c\d\e\f`},
+		{"C:/a/b/c", "./d/e/f", `C:\a\b\c\d\e\f`},
+		{"C:/a/b/c", "../d/e/f", `C:\a\b\c\d\e\f`},
+		{"C:/a/b/c", "../../../windows/system.ini", `C:\a\b\c\windows\system.ini`},
+		{"C:/a/b/c", `C:\windows\system.ini`, `C:\a\b\c\C:\windows\system.ini`},
+		{"C:/a/b/c", `..\..\..\..\C:\windows\system.ini`, `C:\a\b\c\C:\windows\system.ini`},
+		{"C:/a/b/c", `\\server\a\b\c`, `C:\a\b\c\server\a\b\c`},
+		{"C:/a/b/c", `..\..\..\..\\server\a\b\c`, `C:\a\b\c\server\a\b\c`},
+
+		{`\\server\a\b\c`, "", `\\server\a\b\c`},
+		{`\\server\a\b\c`, ".", `\\server\a\b\c`},
+		{`\\server\a\b\c`, "d/e/f", `\\server\a\b\c\d\e\f`},
+		{`\\server\a\b\c`, "./d/e/f", `\\server\a\b\c\d\e\f`},
+		{`\\server\a\b\c`, "../d/e/f", `\\server\a\b\c\d\e\f`},
+		{`\\server\a\b\c`, "../../../windows/system.ini", `\\server\a\b\c\windows\system.ini`},
+		{`\\server\a\b\c`, `C:\windows\system.ini`, `\\server\a\b\c\C:\windows\system.ini`},
+		{`\\server\a\b\c`, `..\..\..\C:\windows\system.ini`, `\\server\a\b\c\C:\windows\system.ini`},
+		{`\\server\a\b\c`, `\\server\a\b\c`, `\\server\a\b\c\server\a\b\c`},
+		{`\\server\a\b\c`, `..\..\..\\server\a\b\c`, `\\server\a\b\c\server\a\b\c`},
+	}
+
+	for _, c := range ts {
+		r := JoinPaths(c.trusted, c.untrusted)
+		if r != c.expected {
+			t.Fatalf("expected '%s', got '%s'. Inputs = '%s', '%s'", c.expected, r, c.trusted, c.untrusted)
+		}
+	}
+}
diff --git a/api/http/handler/customtemplates/customtemplate_file.go b/api/http/handler/customtemplates/customtemplate_file.go
index e238dffb5..2d7d29a88 100644
--- a/api/http/handler/customtemplates/customtemplate_file.go
+++ b/api/http/handler/customtemplates/customtemplate_file.go
@@ -2,7 +2,6 @@ package customtemplates
 
 import (
 	"net/http"
-	"path"
 
 	httperror "github.com/portainer/libhttp/error"
 	"github.com/portainer/libhttp/request"
@@ -41,7 +40,7 @@ func (handler *Handler) customTemplateFile(w http.ResponseWriter, r *http.Reques
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to find a custom template with the specified identifier inside the database", err}
 	}
 
-	fileContent, err := handler.FileService.GetFileContent(path.Join(customTemplate.ProjectPath, customTemplate.EntryPoint))
+	fileContent, err := handler.FileService.GetFileContent(customTemplate.ProjectPath, customTemplate.EntryPoint)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve custom template file from disk", err}
 	}
diff --git a/api/http/handler/edgejobs/edgejob_file.go b/api/http/handler/edgejobs/edgejob_file.go
index 751d56246..e38b9a448 100644
--- a/api/http/handler/edgejobs/edgejob_file.go
+++ b/api/http/handler/edgejobs/edgejob_file.go
@@ -39,7 +39,7 @@ func (handler *Handler) edgeJobFile(w http.ResponseWriter, r *http.Request) *htt
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to find an Edge job with the specified identifier inside the database", err}
 	}
 
-	edgeJobFileContent, err := handler.FileService.GetFileContent(edgeJob.ScriptPath)
+	edgeJobFileContent, err := handler.FileService.GetFileContent("", edgeJob.ScriptPath)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve Edge job script file from disk", err}
 	}
diff --git a/api/http/handler/edgestacks/edgestack_file.go b/api/http/handler/edgestacks/edgestack_file.go
index 7ecafa883..4a791d9c0 100644
--- a/api/http/handler/edgestacks/edgestack_file.go
+++ b/api/http/handler/edgestacks/edgestack_file.go
@@ -2,7 +2,6 @@ package edgestacks
 
 import (
 	"net/http"
-	"path"
 
 	httperror "github.com/portainer/libhttp/error"
 	"github.com/portainer/libhttp/request"
@@ -45,7 +44,7 @@ func (handler *Handler) edgeStackFile(w http.ResponseWriter, r *http.Request) *h
 		fileName = stack.ManifestPath
 	}
 
-	stackFileContent, err := handler.FileService.GetFileContent(path.Join(stack.ProjectPath, fileName))
+	stackFileContent, err := handler.FileService.GetFileContent(stack.ProjectPath, fileName)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve Compose file from disk", err}
 	}
diff --git a/api/http/handler/edgestacks/handler.go b/api/http/handler/edgestacks/handler.go
index d9bf0e39e..72fb27098 100644
--- a/api/http/handler/edgestacks/handler.go
+++ b/api/http/handler/edgestacks/handler.go
@@ -3,7 +3,6 @@ package edgestacks
 import (
 	"fmt"
 	"net/http"
-	"path"
 	"strconv"
 
 	"github.com/gorilla/mux"
@@ -56,7 +55,7 @@ func (handler *Handler) convertAndStoreKubeManifestIfNeeded(edgeStack *portainer
 		return nil
 	}
 
-	composeConfig, err := handler.FileService.GetFileContent(path.Join(edgeStack.ProjectPath, edgeStack.EntryPoint))
+	composeConfig, err := handler.FileService.GetFileContent(edgeStack.ProjectPath, edgeStack.EntryPoint)
 	if err != nil {
 		return fmt.Errorf("unable to retrieve Compose file from disk: %w", err)
 	}
diff --git a/api/http/handler/endpointedge/endpoint_edgestack_inspect.go b/api/http/handler/endpointedge/endpoint_edgestack_inspect.go
index 7f89f128c..cc6cf4594 100644
--- a/api/http/handler/endpointedge/endpoint_edgestack_inspect.go
+++ b/api/http/handler/endpointedge/endpoint_edgestack_inspect.go
@@ -3,7 +3,6 @@ package endpointedge
 import (
 	"errors"
 	"net/http"
-	"path"
 
 	httperror "github.com/portainer/libhttp/error"
 	"github.com/portainer/libhttp/request"
@@ -75,7 +74,7 @@ func (handler *Handler) endpointEdgeStackInspect(w http.ResponseWriter, r *http.
 		}
 	}
 
-	stackFileContent, err := handler.FileService.GetFileContent(path.Join(edgeStack.ProjectPath, fileName))
+	stackFileContent, err := handler.FileService.GetFileContent(edgeStack.ProjectPath, fileName)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve Compose file from disk", err}
 	}
diff --git a/api/http/handler/endpoints/endpoint_status_inspect.go b/api/http/handler/endpoints/endpoint_status_inspect.go
index 9aa9bc4aa..de32502d9 100644
--- a/api/http/handler/endpoints/endpoint_status_inspect.go
+++ b/api/http/handler/endpoints/endpoint_status_inspect.go
@@ -131,7 +131,7 @@ func (handler *Handler) endpointStatusInspect(w http.ResponseWriter, r *http.Req
 			Version:        job.Version,
 		}
 
-		file, err := handler.FileService.GetFileContent(job.ScriptPath)
+		file, err := handler.FileService.GetFileContent("", job.ScriptPath)
 
 		if err != nil {
 			return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve Edge job script file", err}
diff --git a/api/http/handler/stacks/create_compose_stack.go b/api/http/handler/stacks/create_compose_stack.go
index 685fd64d8..4d8c43929 100644
--- a/api/http/handler/stacks/create_compose_stack.go
+++ b/api/http/handler/stacks/create_compose_stack.go
@@ -3,7 +3,6 @@ package stacks
 import (
 	"fmt"
 	"net/http"
-	"path"
 	"strconv"
 	"time"
 
@@ -389,10 +388,9 @@ func (handler *Handler) deployComposeStack(config *composeStackDeploymentConfig)
 		!isAdminOrEndpointAdmin {
 
 		for _, file := range append([]string{config.stack.EntryPoint}, config.stack.AdditionalFiles...) {
-			path := path.Join(config.stack.ProjectPath, file)
-			stackContent, err := handler.FileService.GetFileContent(path)
+			stackContent, err := handler.FileService.GetFileContent(config.stack.ProjectPath, file)
 			if err != nil {
-				return errors.Wrapf(err, "failed to get stack file content `%q`", path)
+				return errors.Wrapf(err, "failed to get stack file content `%q`", file)
 			}
 
 			err = handler.isValidStackFile(stackContent, securitySettings)
diff --git a/api/http/handler/stacks/create_swarm_stack.go b/api/http/handler/stacks/create_swarm_stack.go
index 66f8e230f..6e9b8d3c0 100644
--- a/api/http/handler/stacks/create_swarm_stack.go
+++ b/api/http/handler/stacks/create_swarm_stack.go
@@ -3,7 +3,6 @@ package stacks
 import (
 	"fmt"
 	"net/http"
-	"path"
 	"strconv"
 	"time"
 
@@ -399,8 +398,7 @@ func (handler *Handler) deploySwarmStack(config *swarmStackDeploymentConfig) err
 
 	if !settings.AllowBindMountsForRegularUsers && !isAdminOrEndpointAdmin {
 		for _, file := range append([]string{config.stack.EntryPoint}, config.stack.AdditionalFiles...) {
-			path := path.Join(config.stack.ProjectPath, file)
-			stackContent, err := handler.FileService.GetFileContent(path)
+			stackContent, err := handler.FileService.GetFileContent(config.stack.ProjectPath, file)
 			if err != nil {
 				return errors.WithMessage(err, "failed to get stack file content")
 			}
diff --git a/api/http/handler/stacks/stack_delete.go b/api/http/handler/stacks/stack_delete.go
index 799f6f612..a87bdf847 100644
--- a/api/http/handler/stacks/stack_delete.go
+++ b/api/http/handler/stacks/stack_delete.go
@@ -6,7 +6,6 @@ import (
 	"io/ioutil"
 	"net/http"
 	"os"
-	"path"
 	"strconv"
 
 	"github.com/pkg/errors"
@@ -198,8 +197,8 @@ func (handler *Handler) deleteStack(userID portainer.UserID, stack *portainer.St
 			defer os.RemoveAll(tmpDir)
 
 			for _, fileName := range fileNames {
-				manifestFilePath := path.Join(tmpDir, fileName)
-				manifestContent, err := ioutil.ReadFile(path.Join(stack.ProjectPath, fileName))
+				manifestFilePath := filesystem.JoinPaths(tmpDir, fileName)
+				manifestContent, err := handler.FileService.GetFileContent(stack.ProjectPath, fileName)
 				if err != nil {
 					return errors.Wrap(err, "failed to read manifest file")
 				}
diff --git a/api/http/handler/stacks/stack_file.go b/api/http/handler/stacks/stack_file.go
index e5c5056d3..d0f313505 100644
--- a/api/http/handler/stacks/stack_file.go
+++ b/api/http/handler/stacks/stack_file.go
@@ -2,7 +2,6 @@ package stacks
 
 import (
 	"net/http"
-	"path"
 
 	httperror "github.com/portainer/libhttp/error"
 	"github.com/portainer/libhttp/request"
@@ -82,7 +81,7 @@ func (handler *Handler) stackFile(w http.ResponseWriter, r *http.Request) *httpe
 		}
 	}
 
-	stackFileContent, err := handler.FileService.GetFileContent(path.Join(stack.ProjectPath, stack.EntryPoint))
+	stackFileContent, err := handler.FileService.GetFileContent(stack.ProjectPath, stack.EntryPoint)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve Compose file from disk", err}
 	}
diff --git a/api/http/handler/stacks/update_kubernetes_stack.go b/api/http/handler/stacks/update_kubernetes_stack.go
index 9ce74cb6c..4eda081e4 100644
--- a/api/http/handler/stacks/update_kubernetes_stack.go
+++ b/api/http/handler/stacks/update_kubernetes_stack.go
@@ -5,7 +5,6 @@ import (
 	"io/ioutil"
 	"net/http"
 	"os"
-	"path"
 	"strconv"
 
 	"github.com/asaskevich/govalidator"
@@ -108,7 +107,7 @@ func (handler *Handler) updateKubernetesStack(r *http.Request, stack *portainer.
 	tempFileDir, _ := ioutil.TempDir("", "kub_file_content")
 	defer os.RemoveAll(tempFileDir)
 
-	if err := filesystem.WriteToFile(path.Join(tempFileDir, stack.EntryPoint), []byte(payload.StackFileContent)); err != nil {
+	if err := filesystem.WriteToFile(filesystem.JoinPaths(tempFileDir, stack.EntryPoint), []byte(payload.StackFileContent)); err != nil {
 		return &httperror.HandlerError{StatusCode: http.StatusInternalServerError, Message: "Failed to persist deployment file in a temp directory", Err: err}
 	}
 
diff --git a/api/http/handler/templates/template_file.go b/api/http/handler/templates/template_file.go
index 844e99e16..e5b5c3d4a 100644
--- a/api/http/handler/templates/template_file.go
+++ b/api/http/handler/templates/template_file.go
@@ -4,7 +4,6 @@ import (
 	"errors"
 	"log"
 	"net/http"
-	"path"
 
 	"github.com/asaskevich/govalidator"
 	httperror "github.com/portainer/libhttp/error"
@@ -68,9 +67,7 @@ func (handler *Handler) templateFile(w http.ResponseWriter, r *http.Request) *ht
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to clone git repository", err}
 	}
 
-	composeFilePath := path.Join(projectPath, payload.ComposeFilePathInRepository)
-
-	fileContent, err := handler.FileService.GetFileContent(composeFilePath)
+	fileContent, err := handler.FileService.GetFileContent(projectPath, payload.ComposeFilePathInRepository)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Failed loading file content", err}
 	}
diff --git a/api/internal/stackutils/stackutils.go b/api/internal/stackutils/stackutils.go
index 4945eeaa1..0d8b92e6b 100644
--- a/api/internal/stackutils/stackutils.go
+++ b/api/internal/stackutils/stackutils.go
@@ -3,7 +3,6 @@ package stackutils
 import (
 	"fmt"
 	"io/ioutil"
-	"path"
 
 	"github.com/pkg/errors"
 	portainer "github.com/portainer/portainer/api"
@@ -20,7 +19,7 @@ func ResourceControlID(endpointID portainer.EndpointID, name string) string {
 func GetStackFilePaths(stack *portainer.Stack) []string {
 	var filePaths []string
 	for _, file := range append([]string{stack.EntryPoint}, stack.AdditionalFiles...) {
-		filePaths = append(filePaths, path.Join(stack.ProjectPath, file))
+		filePaths = append(filePaths, filesystem.JoinPaths(stack.ProjectPath, file))
 	}
 	return filePaths
 }
@@ -37,8 +36,8 @@ func CreateTempK8SDeploymentFiles(stack *portainer.Stack, kubeDeployer portainer
 	}
 
 	for _, fileName := range fileNames {
-		manifestFilePath := path.Join(tmpDir, fileName)
-		manifestContent, err := ioutil.ReadFile(path.Join(stack.ProjectPath, fileName))
+		manifestFilePath := filesystem.JoinPaths(tmpDir, fileName)
+		manifestContent, err := ioutil.ReadFile(filesystem.JoinPaths(stack.ProjectPath, fileName))
 		if err != nil {
 			return nil, "", errors.Wrap(err, "failed to read manifest file")
 		}
diff --git a/api/portainer.go b/api/portainer.go
index b2803f38b..43703bc4c 100644
--- a/api/portainer.go
+++ b/api/portainer.go
@@ -1212,7 +1212,7 @@ type (
 	// FileService represents a service for managing files
 	FileService interface {
 		GetDockerConfigPath() string
-		GetFileContent(filePath string) ([]byte, error)
+		GetFileContent(trustedRootPath, filePath string) ([]byte, error)
 		Copy(fromFilePath string, toFilePath string, deleteIfExists bool) error
 		Rename(oldPath, newPath string) error
 		RemoveDirectory(directoryPath string) error