An updated thunderbird package that fixes one security issue is now available for Red Hat Enterprise Linux 4, 5, and 6. The Red Hat Security Response Team has rated this update as having important security impact. Description Mozilla Thunderbird is a standalone mail and newsgroup client. It was found that a Certificate Authority issued a fraudulent HTTPS certificate. This update renders any HTTPS certificates signed by that CA as untrusted, except for a select few. The now untrusted certificates that were issued before July 1, 2011 can be manually re-enabled and used again at your own risk in Thunderbird; however, affected certificates issued after this date cannot be re-enabled or used. All Thunderbird users should upgrade to this updated package, which resolves this issue. All running instances of Thunderbird must be restarted for the update to take effect.