CVE 2013-0756
Use-after-free vulnerability in the obj_toSource function in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderbird ESR 17.x before 17.0.2, and SeaMonkey before 2.15 allows remote attackers to execute arbitrary code via a crafted web page referencing JavaScript Proxy objects that are not properly handled during garbage collection.
See the 
CVE page on Mitre.org
for more details.
