diff --git a/infra/conf/transport_internet.go b/infra/conf/transport_internet.go
index 2f3b8009..89dfa645 100644
--- a/infra/conf/transport_internet.go
+++ b/infra/conf/transport_internet.go
@@ -628,6 +628,9 @@ func (c *REALITYConfig) Build() (proto.Message, error) {
 		}
 		config.ShortIds = make([][]byte, len(c.ShortIds))
 		for i, s := range c.ShortIds {
+			if len(s) > 16 {
+				return nil, errors.New(`too long "shortIds[`, i, `]": `, s)
+			}
 			config.ShortIds[i] = make([]byte, 8)
 			if _, err = hex.Decode(config.ShortIds[i], []byte(s)); err != nil {
 				return nil, errors.New(`invalid "shortIds[`, i, `]": `, s)
@@ -679,6 +682,9 @@ func (c *REALITYConfig) Build() (proto.Message, error) {
 		if len(c.ShortIds) != 0 {
 			return nil, errors.New(`non-empty "shortIds", please use "shortId" instead`)
 		}
+		if len(c.ShortIds) > 16 {
+			return nil, errors.New(`too long "shortId": `, c.ShortId)
+		}
 		config.ShortId = make([]byte, 8)
 		if _, err = hex.Decode(config.ShortId, []byte(c.ShortId)); err != nil {
 			return nil, errors.New(`invalid "shortId": `, c.ShortId)