Ubuntu Security Notice 2673-1 – Karthikeyan Bhargavan discovered that NSS incorrectly handled state transitions for the TLS state machine. If a remote attacker were able to perform a man-in-the-middle attack, this flaw could be exploited to skip the ServerKeyExchange message and remove the forward-secrecy property. Bob Clary, Christian Holler, Bobby Holley, and Andrew McCreight discovered multiple memory safety issues in Thunderbird. If a user were tricked in to opening a specially crafted website in a browsing context, an attacker could potentially exploit these to cause a denial of service via application crash, or execute arbitrary code with the privileges of the user invoking Thunderbird. Various other issues were also addressed.