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Mozilla Foundation Security Advisory 2009-51

Title: Chrome privilege escalation with FeedWriter
Impact: Critical
Announced: September 9, 2009
Reporter: moz_bug_r_a4
Products: Firefox

Fixed in: Firefox 3.5.3
  Firefox 3.0.14


Mozilla security researcher moz_bug_r_a4 reported that the BrowserFeedWriter could be leveraged to run JavaScript code from web content with elevated privileges. Using this vulnerability, an attacker could construct an object containing malicious JavaScript and cause the FeedWriter to process the object, running the malicious code with chrome privileges.

Thunderbird does not support the BrowserFeedWriter object and is not vulnerable in its default configuration. Thunderbird might be vulnerable if the user has installed any add-on which adds a similarly implemented feature and then enables JavaScript in mail messages. This is not the default setting and we strongly discourage users from running JavaScript in mail.


Disable JavaScript until a version containing this fix can be installed.