Ensure we fail with a decode error alert if the server sends and empty Cert
@@ -1688,7 +1688,8 @@ MSG_PROCESS_RETURN tls_process_server_certificate(SSL *s, PACKET *pkt)
if ((SSL_IS_TLS13(s) && !PACKET_get_1(pkt, &context))
|| context != 0
|| !PACKET_get_net_3(pkt, &cert_list_len)
- || PACKET_remaining(pkt) != cert_list_len) {
+ || PACKET_remaining(pkt) != cert_list_len
+ || PACKET_remaining(pkt) == 0) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_TLS_PROCESS_SERVER_CERTIFICATE, SSL_R_LENGTH_MISMATCH);
goto f_err;
