| Mozilla Network Security Services (NSS) before 3.19, as used in
Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 38.x
before 38.1, Thunderbird before 38.1, and other products, does not
properly determine state transitions for the TLS state machine, which
allows man-in-the-middle attackers to defeat cryptographic protection
mechanisms by blocking messages, as demonstrated by removing a
forward-secrecy property by blocking a ServerKeyExchange message, aka
a "SMACK SKIP-TLS" issue.
|