Mozilla has released Thunderbird 3.1.6 and Thunderbird 3.0.10, each of which fixes a single critical security issue that could potentially allow remote code execution. Two versions of the update are available depending upon the version of Thunderbird installed. All Thunderbird 3.1 and 3.0 users should apply the update as soon as possible.
This issue does not affect email or newsgroups but could be triggered through browser-like features or add-ons.
For more information, see