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?
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