User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the nsXULCommandDispatcher.cpp source code. During a NS_XUL_COMMAND_UPDATE event dispatch, the user is able to force command dispatcher to remove all the updaters in the mUpdaters chain including the one that is currently in use. As a result, the local variable updater becomes a stale pointer and updater->mNext refers to memory previously freed. Successful exploitation can lead to code execution in the context of the browser.