Vulnerable Systems:
* Mozilla Firefox 19.0.1
* Mozilla Thunderbird 17.0.3
* Mozilla SeaMonkey 2.16
* Mozilla Firefox ESR 17.0.3
* Mozilla Thunderbird ESR 17.0.3
Multiple Mozilla products contain a use-after-free error in the HTML editor that is triggered when content script is run by the 'document.execCommand' function while internal editor operations are occurring. With a specially crafted web page, a context-dependent attacker can dereference already freed memory to execute arbitrary code.