1 files changed, 16 insertions, 2 deletions

diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index 646c59e5d6..60daff6f8d 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.9 2017/08/12 23:38:12 beck Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.10 2017/08/23 15:39:38 doug Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -130,7 +130,21 @@ tlsext_ec_serverhello_build(SSL *s, CBB *cbb)
 int
 tlsext_ec_serverhello_parse(SSL *s, CBS *cbs, int *alert)
 {
-        return 0;
+        /*
+         * Servers should not send this extension per the RFC.
+         *
+         * However, F5 sends it by mistake (case ID 492780) so we need to skip
+         * over it.  This bug is from at least 2014 but as of 2017, there
+         * are still large sites with this bug in production.
+         *
+         * https://devcentral.f5.com/questions/disable-supported-elliptic-curves-extension-from-server
+         */
+        if (!CBS_skip(cbs, CBS_len(cbs))) {
+                *alert = TLS1_AD_INTERNAL_ERROR;
+                return 0;
+        }
+
+        return 1;
 }
 
 /*