Mozilla Thunderbird is a standalone mail and newsgroup client.It was found that a Certificate Authority (CA) issued a fraudulent HTTPScertificate. This update renders any HTTPS certificates signed by thatCA as untrusted, except for a select few. The now untrusted certificatesthat were issued before July 1, 2011 can be manually re-enabled and usedagain at your own risk in Thunderbird; however, affected certificatesissued after this date cannot be re-enabled or used. (BZ#734316)All Thunderbird users should upgrade to this updated package, whichresolves this issue. All running instances of Thunderbird must berestarted for the update to take effect.