diff --git a/net/ipv6/fou6.c b/net/ipv6/fou6.c
index bd675c61deb1fcc6bfe9f332637590451327fd05..7da7bf3b7fe3953eeb60addfffd6687c4da582c4 100644
--- a/net/ipv6/fou6.c
+++ b/net/ipv6/fou6.c
@@ -131,6 +131,14 @@ static int gue6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	if (validate_gue_flags(guehdr, optlen))
 		return -EINVAL;
 
+	/* Handling exceptions for direct UDP encapsulation in GUE would lead to
+	 * recursion. Besides, this kind of encapsulation can't even be
+	 * configured currently. Discard this.
+	 */
+	if (guehdr->proto_ctype == IPPROTO_UDP ||
+	    guehdr->proto_ctype == IPPROTO_UDPLITE)
+		return -EOPNOTSUPP;
+
 	skb_set_transport_header(skb, -(int)sizeof(struct icmp6hdr));
 	ret = gue6_err_proto_handler(guehdr->proto_ctype, skb,
 				     opt, type, code, offset, info);