A security bug in Netscape and Mozilla browsers could allow a malicious web site operator to access cookies on users' computers.

The vulnerability, which affects Netscape older than 6.2.1 and versions of Mozilla prior to 0.9.7, allows an attacker to steal a user's cookies - if he succeeds in tricking a victim into visiting a particular URL.

Cookies are often used to identify and authenticate users to a Web site. If an attacker can steal a user's cookies, then they can impersonate that user. How much damage could be caused through this is dependent on how a particular site uses the cookies.

Although Netscape states it is not aware of active exploitation of the bug, the issue is a concern because the exploit could be conducted with something as simple as an image tag in a Web page or email pointing at a maliciously crafted URL. There's no requirement for active scripting to be enabled for the vulnerability to work.

Netscape advises users to upgrade to the recently released version 6.2.1 of its browser or Mozilla 0.9.7, which are free of the vulnerability. Netscape Communicator 4.x is also immune from the glitch. ®

External links

Netscape's security advice
Unofficial cookie FAQ
Analysis by Marc Slemko, who discovered the bug