Mozilla Thunderbird is a standalone mail and newsgroup client. Several flaws were found in the processing of malformed web content. A web page containing malicious content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. A use-after-free flaw was found in the way Thunderbird resolved hosts in certain circumstances. An attacker could use this flaw to crash Thunderbird or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. An out-of-bounds read flaw was found in the way Thunderbird decoded JPEG images. Loading an email or a web page containing a specially crafted JPEG image could cause Thunderbird to crash. A flaw was found in the way Thunderbird handled browser navigations through history. An attacker could possibly use this flaw to cause the address bar of the browser to display a web page name while loading content from an entirely different web page, which could allow for cross-site scripting attacks. Red Hat would like to thank the Mozilla project for reporting these issues. Upstream acknowledges Bobby Holley, Carsten Book, Christoph Diehl, Gary Kwong, Jan de Mooij, Jesse Ruderman, Nathan Froyd, Christian Holler, Abhishek Arya, Mariusz Mlynski, moz_bug_r_a4, Nils, Tyson Smith and Jesse Schwartzentrube as the original reporters of these issues. Note: All of the above issues cannot be exploited by a specially crafted HTML mail message as JavaScript is disabled by default for mail messages. They could be exploited another way in Thunderbird, for example, when viewing the full remote content of an RSS feed. For technical details regarding these flaws, refer to the Mozilla security advisories for Thunderbird 24.5.0. You can find a link to the Mozilla advisories in the References section of this erratum. All Thunderbird users should upgrade to this updated package, which contains Thunderbird version 24.5.0, which corrects these issues. After installing the update, Thunderbird must be restarted for the changes to take effect.