Man-in-the-Middle (MitM)

nss is vulnerable to man-in-the-middle attack. A flaw was found in the way TLS 1.2 could use the MD5 hash function for signing ServerKeyExchange and Client Authentication packets during a TLS handshake. A man-in-the-middle attacker able to force a TLS connection to use the MD5 hash function could use this flaw to conduct collision attacks to impersonate a TLS server or an authenticated TLS client.