Mozilla Foundation Security Advisory 2013-113
Title: Trust settings for built-in roots ignored
during EV certificate validation
Announced: December 10, 2013
Reporter: Sijie Xia
Products: Firefox, Thunderbird, Seamonkey
Fixed in: Firefox 26
Firefox ESR 24.2
Firefox user Sijie Xia reported that if a user explicitly removes the trust for extended validation (EV) capable root certificates in the certificate manager, the change is not properly used when validating EV certificates, causing the setting to be ignored. This removes the ability of users to explicitly untrust root certificates from specific certificate authorities.
This flaw does not affect certificates that are not extended validation certificates. All other certificate validation checks do occur, the error is the assumption that if Mozilla trusted the certificate, the user would also.