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