Software Engineering Institute

The Mozilla browser engine contains several vulnerabilities that may result in memory corruption. The impact of this memory corruption in specific cases is unclear. According to Mozilla Foundation Security Advisory MFSA 2007-29:

As part of the Firefox 2.0.0.8 update releases Mozilla developers fixed many bugs to improve the stability of the product. 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.
Information about the individual flaws causing the vulnerabilities addressed in this update can be found in the references section of this document.
Note that the Thunderbird email client also uses the Mozilla browser engine and could be affected by these vulnerabilities if JavaScript is enabled (it is disabled by default).

Potential impacts of these vulnerabilities include remote execution of arbitrary code and denial of service.

Upgrade
These vulnerabilities are addressed in Firefox 2.0.0.8, Thunderbird 2.0.0.8, and SeaMonkey 1.1.5.

Users that are unable to update should consider the following workaround:

Disable JavaScript

For instructions on how to disable JavaScript in Firefox, please refer to the Firefox section of the Securing Your Web Browser document.
Note that disabling JavaScript may not completely mitigate these vulnerabilities. Exploitation methods using JavaScript are common, however the Mozilla Security Team also suggests that other techniques such as large images could be used to exploit these vulnerabilities.