Security researcher Oriol reported memory corruption when local files are modified (by either the user or another program) at the same time being read using the FileReader API. This flaw requires that input be taken from a local file in order to be triggered and cannot be triggered by web content. This results in a potentially exploitable crash when triggered.
Name: The Mozilla Project
This issue does not affect the version of firefox and thunderbird as shipped with Red Hat Enterprise Linux 5, 6 and 7.