Mozilla Foundation Security Advisory 2009-34

Crashes with evidence of memory corruption (rv:1.9.1/

July 21, 2009
Mozilla developers and community
Fixed in
  • Firefox 3.0.12
  • Firefox 3.5


Mozilla developers and community members 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.


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


Martijn Wargers, Arno Renevier, Jesse Ruderman, Olli Pettay and Blake Kaplan reported crashes in the Firefox 3 and Firefox 3.5 browser engines. monarch2020 reported an integer overflow in a base64 decoding function. Christophe Charron reported a crash occuring when multiple RDF files were loaded in a XUL tree element. Yongqian Li reported that a document can be constructed whose internal representation contains double copies of certain elements leading to potentially unsafe memory conditions. John Senchak also separately reported a double frame construction bug which could also be used to crash the browser and run arbitrary code.

Peter Van der Beken, Mike Shaver, Jesse Ruderman, and Carsten Book reported crashes in the Firefox 3 and Firefox 3.5 JavaScript engines.