CVE 2012-3962
Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 do not properly iterate through the characters in a text run, which allows remote attackers to execute arbitrary code via a crafted document.
See the 
CVE page on Mitre.org
for more details.
