Incorrect boundary conditions, integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

A flaw was found in the way NSS verifies certificates. That will happen both when client reads the Certificate message from the server or when server is configured to ask for client certificates and then receives one.

Firefox is not vulnerable as it uses the mozilla::pkix for certificate verification. Crucially, NSS fully parses the certificate before any other checks, so disabled signature methods or certificate types don't impact exploitability.

Any TLS and DTLS client that does use NSS built in certificate verification routines is vulnerable as well as any server that has certificate based client authentication enabled.

But the issue is not limited to TLS, any applications that use certificate verification are vulnerable, S/MIME is impacted too.

Marsh Ray of PhoneFactor has discovered a flaw in the TLS/SSL protocol related to the handling of the session rehandshakes / renegotiations. This flaw can possibly be used in the MITM attacks and allowing an attacker to inject attacker-chosen plain text prefix to the session of the victim.

Further details are available in the "Authentication Gap in TLS Renegotiation" blog post: http://extendedsubset.com/?p=8