Mozilla Thunderbird is a standalone mail and newsgroup client.
Several flaws were found in the processing of malformed content. Malicious content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. (CVE-2013-0775, CVE-2013-0780, CVE-2013-0782, CVE-2013-0783)
It was found that, after canceling a proxy server's authentication prompt, the address bar continued to show the requested site's address. An attacker could use this flaw to conduct phishing attacks by tricking a user into believing they are viewing trusted content. (CVE-2013-0776)
Red Hat would like to thank the Mozilla project for reporting these issues. Upstream acknowledges Nils, Abhishek Arya, Olli Pettay, Christoph Diehl, Gary Kwong, Jesse Ruderman, Andrew McCreight, Joe Drew, Wayne Mery, and Michal Zalewski as the original reporters of these issues.
Important: This erratum upgrades Thunderbird to version 17.0.3 ESR. Thunderbird 17 is not completely backwards-compatible with all Mozilla add-ons and Thunderbird plug-ins that worked with Thunderbird 10.0. Thunderbird 17 checks compatibility on first-launch, and, depending on the individual configuration and the installed add-ons and plug-ins, may disable said Add-ons and plug-ins, or attempt to check for updates and upgrade them. Add-ons and plug-ins may have to be manually updated.
All Thunderbird users should upgrade to this updated package, which contains Thunderbird version 17.0.3 ESR, which corrects these issues. After installing the update, Thunderbird must be restarted for the changes to take effect.