Mozilla Foundation Security Advisory 2009-14

Crashes with evidence of memory corruption (rv:

April 21, 2009
Mozilla developers
Firefox, SeaMonkey, Thunderbird
Fixed in
  • Firefox 3.0.9
  • SeaMonkey 1.1.16
  • Thunderbird


Mozilla developers identified and fixed several stability bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these crashes showed evidence of memory corruption under certain circumstances and we presume that with enough effort at least some of these could be exploited to run arbitrary code.

Thunderbird shares the browser engine with Firefox and could be vulnerable if JavaScript were to be enabled in mail. This is not the default setting and we strongly discourage users from running JavaScript in mail. Without further investigation we cannot rule out the possibility that for some of these an attacker might be able to prepare memory for exploitation through some means other than JavaScript such as large images.


Disable JavaScript until a version containing these fixes can be installed.


Olli Pettay, Martijn Wargers, Mats Palmgren, Oleg Romashin, Jesse Ruderman, and Gary Kwong reported crashes in the Firefox 3 browser engine. One of the crashes also affects Firefox 2 as well.

Igor Bukanov and Bob Clary reported crashes in the Firefox 3 JavaScript engine. One of the crashes affects Firefox 2 as well.