Software Engineering Institute

The Mozilla Firefox QueryInterface method contains a memory corruption vulnerability. According to Mozilla:

Calling the QueryInterface method of the built-in Location and Navigator objects causes memory corruption that 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, but not in the Mozilla's mail client or Thunderbird. Exploitation can occur by accessing a specially crafted web page with Firefox. If JavaScript is enabled within Mozilla's mail client or Thunderbird, then this issue may be exploitable by opening a specially crafted email.

We are aware of working exploit code for this vulnerability.

A remote, unauthenticated attacker may be able to execute arbitrary code on a vulnerable system.

Upgrade
This issue is fixed in Firefox 1.5.0.1 and SeaMonkey 1.0.

Disable JavaScript in Firefox

Users who are unable to upgrade to a fixed version of the software are encouraged to disable JavaScript in the Firefox web browser and Thunderbird.