The ssl3_send_client_key_exchange function in s3_clnt.c in OpenSSL before 0.9.8za, 1.0.0 before 1.0.0m, and 1.0.1 before 1.0.1h, when an anonymous ECDH cipher suite is used, allows remote attackers to cause a denial of service (NULL pointer dereference and client crash) by triggering a NULL certificate value. diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c index c99a4c4..0457af8 100644 (file) --- a/ssl/s3_clnt.c +++ b/ssl/s3_clnt.c @@ -2512,6 +2512,13 @@ int ssl3_send_client_key_exchange(SSL *s) int ecdh_clnt_cert = 0; int field_size = 0; + if (s->session->sess_cert == NULL) + { + ssl3_send_alert(s,SSL3_AL_FATAL,SSL_AD_UNEXPECTED_MESSAGE); + SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE,SSL_R_UNEXPECTED_MESSAGE); + goto err; + } + /* Did we send out the client's * ECDH share for use in premaster * computation as part of client certificate?