Mozilla Firefox before 31.0 and Thunderbird before 31.0 allow remote attackers to cause a denial of service (X.509 certificate parsing outage) via a crafted certificate that does not use ASCII character encoding in a required context.
https://security.gentoo.org/glsa/201504-01
https://bugzilla.mozilla.org/show_bug.cgi?id=997795
http://www.securitytracker.com/id/1030620
http://www.securitytracker.com/id/1030619
http://www.mozilla.org/security/announce/2014/mfsa2014-65.html