ssh: fix incorrect operator order

thatnealpatel · gopherbot · commit abbc44d451a6 · 2026-05-21T17:03:25.000-07:00
Arithmetic is incorrectly applied to 'byte' instead of 'int' resulting in a possible overflow that allows for a panic. Fixes CVE-2026-46597 Fixes golang/go#79561 Change-Id: I83edabeeda676f0209d29d5e2554890bbd0eef8f Reviewed-on: https://go-review.googlesource.com/c/crypto/+/781620 Reviewed-by: Roland Shoemaker <roland@golang.org> Auto-Submit: Gopher Robot <gobot@golang.org> Reviewed-by: Nicholas Husin <nsh@golang.org> Reviewed-by: Nicholas Husin <husin@google.com> LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/ssh/cipher.go b/ssh/cipher.go
@@ -407,7 +407,7 @@ func (c *gcmCipher) readCipherPacket(seqNum uint32, r io.Reader) ([]byte, error)
 		return nil, fmt.Errorf("ssh: illegal padding %d", padding)
 	}
 
-	if int(padding+1) >= len(plain) {
+	if int(padding)+1 >= len(plain) {
 		return nil, fmt.Errorf("ssh: padding %d too large", padding)
 	}
 	plain = plain[1 : length-uint32(padding)]

Original file line number	Diff line number	Diff line change
`@@ -407,7 +407,7 @@ func (c *gcmCipher) readCipherPacket(seqNum uint32, r io.Reader) ([]byte, error)`
`407`	`407`	`return nil, fmt.Errorf("ssh: illegal padding %d", padding)`
`408`	`408`	`}`
`409`	`409`
`410`		`- if int(padding+1) >= len(plain) {`
	`410`	`+ if int(padding)+1 >= len(plain) {`
`411`	`411`	`return nil, fmt.Errorf("ssh: padding %d too large", padding)`
`412`	`412`	`}`
`413`	`413`	`plain = plain[1 : length-uint32(padding)]`