Fedora has issued an update for thunderbird and sunbird. This fixes multiple vulnerabilities, which can be exploited by malicious, local users to gain escalated privileges, and by malicious people to conduct spoofing attacks, bypass certain security restrictions, and potentially compromise a user's system.

For more information:
SA41244
SA41890
SA41975

Solution
Apply updated packages using the yum utility ("yum update thunderbird sunbird").
Original Advisory
FEDORA-2010-16941:
http://lists.fedoraproject.org/pipermail/package-announce/2010-November/050216.html
http://lists.fedoraproject.org/pipermail/package-announce/2010-November/050217.html

FEDORA-2010-16939:
http://lists.fedoraproject.org/pipermail/package-announce/2010-November/050192.html
http://lists.fedoraproject.org/pipermail/package-announce/2010-November/050191.html

Other references
Further details available to Secunia VIM customers

Deep Links
Links available to Secunia VIM customers