diff --git a/auth.c b/auth.c
index 0dbbc48c2..4f541e18d 100644
--- a/auth.c
+++ b/auth.c
@@ -636,6 +636,9 @@ int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
 		if (blob_len < (u64)sess_key_off + sess_key_len)
 			return -EINVAL;
 
+		if (sess_key_len > CIFS_KEY_SIZE)
+			return -EINVAL;
+
 		ctx_arc4 = kmalloc(sizeof(*ctx_arc4), GFP_KERNEL);
 		if (!ctx_arc4)
 			return -ENOMEM;