Posts Tagged ‘JIT’

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