CVE-2015-7575: Medium severity IBM Cognos Analytics vulnerability

A new class of transcript collision attacks on the use of MD5 in key exchange protocol was found in TLS 1.2. Due to several high-profile attacks against MD5, there is now consensus among certification authorities and software vendors to stop issuing and accepting new MD5 certificates. However MD5 continues to be supported in key exchange protocol for TLS 1.2 and also in IPSec and SSH-2. A almost-practical impersonation and downgrade attack was demostrated for IKEv2 and SSH-2 and also a concrete credential forwarding attack against TLS 1.2 client authentication.

— Red Hat

Mozilla Network Security Services (NSS) before 3.20.2, as used in Mozilla Firefox before 43.0.2 and Firefox ESR 38.x before 38.5.2, does not reject MD5 signatures in Server Key Exchange messages in TLS 1.2 Handshake Protocol traffic, which makes it easier for man-in-the-middle attackers to spoof servers by triggering a collision.

The TLS protocol could allow weaker than expected security caused by a collision attack when using the MD5 hash function for signing a ServerKeyExchange message during a TLS handshake. An attacker could exploit this vulnerability using man-in-the-middle techniques to impersonate a TLS server and obtain credentials.

— IBM