CVE-2016-6306: Medium severity OpenSSL OpenSSL vulnerability

Multiple out of bounds read flaws were found in the way OpenSSL handled certain TLS/SSL protocol handshake messages. A remote attacker could possibly use these flaws to crash a TLS/SSL server or client using OpenSSL.

Quoting form the draft of the OpenSSL upstream advisory:

Certificate message OOB reads (CVE-2016-6306) =============================================

Severity: Low

In OpenSSL 1.0.2 and earlier some missing message length checks can result in OOB reads of up to 2 bytes beyond an allocated buffer. There is a theoretical DoS risk but this has not been observed in practice on common platforms.

The messages affected are client certificate, client certificate request and server certificate. As a result the attack can only be performed against a client or a server which enables client authentication.

OpenSSL 1.1.0 is not affected.

OpenSSL 1.0.2 users should upgrade to 1.0.2i OpenSSL 1.0.1 users should upgrade to 1.0.1u

This issue was reported to OpenSSL on 22nd August 2016 by Shi Lei (Gear Team, Qihoo 360 Inc.). The fix was developed by Stephen Henson of the OpenSSL development team.

— Red Hat

The certificate parser in OpenSSL before 1.0.1u and 1.0.2 before 1.0.2i might allow remote attackers to cause a denial of service (out-of-bounds read) via crafted certificate operations, related to s3clnt.c and s3srvr.c.