Software Engineering Institute

Mozilla products contain a vulnerability in the browser engine that may result in information disclosure or a denial of service when handling malicious image files when a user leaves a page with designMode frames. According to the Mozilla Foundation Security Advisory 2008-06:

The reported issue can be used to steal a user's navigation history, forward navigation information, and crash the user's browser. The crash showed evidence of memory corruption and might be exploitable to run arbitrary code.

Note that JavaScript must be enabled in order for this vulnerability to exist. JavaScript is enabled by default in the Firefox and Mozilla web browsers. Exploitation can occur by accessing a specially crafted web page with Firefox.

A remote, unauthorized attacker may be able to view browser history information or cause a denial of service.

Apply an update
According to the Mozilla Foundation Security Advisory 2008-06 this vulnerability is addressed in Firefox 2.0.0.12 and SeaMonkey 1.1.8

Disable JavaScript

For instructions on how to disable JavaScript in Firefox, please refer to the Firefox section of the Securing Your Web Browser document.

Use NoScript

Using the Mozilla Firefox NoScript extension to whitelist web sites that can run scripts and access installed plugins will mitigate this vulnerability.