Users who use Firefox 3.5 need to know that, there is critical JavaScript vulnerability in Firefox web browser.

The flaw is known as Zero-day flaw and its in Firefox 3.5’s Just-in-time (JIT) JavaScript compiler.

The Impact it can make:

The vulnerability can be exploited by an attacker who tricks a victim into viewing a malicious Web page containing the exploit code. The vulnerability can be mitigated by disabling the JIT in the JavaScript engine. To do so:

1. Enter about:config in the browser’s location bar.
2. Type jit in the Filter box at the top of the config editor.
3. Double-click the line containing javascript.options.jit.content setting the value to false.

Note that disabling the JIT will result in decreased JavaScript performance and is only recommended as a temporary security measure.  Once users have been received the security update containing the fix for this issue, they should restore the JIT setting to true by:

1. Enter about:config in the browser’s location bar.
2. Type jit in the Filter box at the top of the config editor.
3. Double-click the line containing javascript.options.jit.content setting the value to true.

A company named Secunia has rated this vulnerability as very high——- Click Here

Read More: Firefox Blog

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