Mozilla has announced a critical vulnerability in the newly released Firefox 3.5
It is possible that other versions of Firefox have this vulnerability which allows a user’s computer to be exploited by others executing code on it.
The Firefox 3.5 vulnerability arises through a bug in the Just-in-time (JIT) JavaScript compiler. This causes memory corruption by a Javascript code-handling error when faced with certain HTML tags.
To reduce the risk of exploitation it is advised that you disable the JIT for now. Here’s how:
- Enter about:config in the browser’s location bar.
- Type jit in the Filter box at the top of the config editor.
- Double-click the line containing javascript.options.jit.content setting the value to false.
(Or you could use Safari…)
Anyway, as this will cause performance loss, once a bugfix is released you should swith the JIT back on by:
- Enter about:config in the browser’s location bar.
- Type jit in the Filter box at the top of the config editor.
- Double-click the line containing javascript.options.jit.content setting the value to true.
UPDATE: 09:45hrs 17th July 2009: This critical vulnerability has now been fixed with the release of Firefox 3.5.1
Tags: Firefox, Javascript, JIT, Safari, Security
[...] the discovery earlier this week that there was a critical vulnerability in Firefox 3.5’s Just-In-Time Javascript compiler has meant that 3.5.1 has been released even earlier than intended to fix the vulnerability and [...]