(RHSA-2012:0140) Critical: thunderbird security update

Mozilla Thunderbird is a standalone mail and newsgroup client.

A heap-based buffer overflow flaw was found in the way Thunderbird handled
PNG (Portable Network Graphics) images. An HTML mail message or remote
content containing a specially-crafted PNG image could cause Thunderbird to
crash or, possibly, execute arbitrary code with the privileges of the user
running Thunderbird. (CVE-2011-3026)

All Thunderbird users should upgrade to this updated package, which
corrects this issue. After installing the update, Thunderbird must be
restarted for the changes to take effect.