A weakness and some vulnerabilities have been reported in Mozilla Firefox and SeaMonkey, which can be exploited by malicious people to conduct spoofing attacks, cross-site request forgery attacks, and compromise a user's system.

1) Multiple errors in the browser engine can be exploited to corrupt memory and potentially execute arbitrary code.

2) An error when handling recursive calls to "eval()" within a "try/catch" statement can lead to dialogs being displayed incorrectly and returning "true" when being closed. This can e.g. be exploited to gain escalated privileges by forcing a user into accepting certain dialogs.

3) A use-after-free error in the js3250.dll library when processing the "JSON.stringify()" method can be exploited to dereference an invalid pointer in a call to the "js_HasOwnProperty()" function.

4) An error within the internal memory mapping of non-local JavaScript variables can be exploited to cause a buffer overflow and potentially execute arbitrary code.

5) An error within the internal string mapping of the JavaScript engine related to an offset pointer when handling more than 64K values can be exploited to cause an exception object to be read from invalid memory.

6) A use-after-free error related to JavaScript "Workers" can be exploited to dereference invalid memory and execute arbitrary code.

7) An error when allocating memory for layout objects displaying long strings can be exploited to cause a memory corruption and execute arbitrary code.

Note: This may only affect the Windows platform.

8) The "ParanoidFragmentSink" class does not properly filter "javascript:" URLs and inline JavaScript, which can be exploited to execute arbitrary JavaScript code.

Successful exploitation requires that e.g. an extension using the function to sanitise HTML code before embedding it in a chrome document is installed.

9) An error when decoding certain JPEG images can be exploited to cause a buffer overflow and potentially execute arbitrary code.

Note: This does not affect the Mozilla Firefox 3.5 branch.

10) When a request initiated by the plugin received a redirect response (307), the request including any custom headers is incorrectly forwarded to the new location without notifying the plugin, which can be used to e.g. bypass cross-site request forgery protections relying on custom headers.

Solution
Update to Mozilla Firefox version 3.5.17 or 3.6.14 and Mozilla SeaMonkey version 2.0.12.

Provided and/or discovered by
3) regenrecht, via ZDI
8) Reported by the vendor

The vendor credits:
1) Jesse Ruderman, Igor Bukanov, Olli Pettay, Gary Kwong, Jeff Walden, Henry Sivonen, Martijn Wargers, David Baron, and Marcia Knous
2) Zach Hoffman
4, 5) Christian Holler
6) Daniel Kozlowski
7) Alex Miller
9) Jordi Chancel
10) Peleus Uhley, Adobe

Changelog
Further details available in Customer Area

Original Advisory
1) http://www.mozilla.org/security/announce/2011/mfsa2011-01.html
2) http://www.mozilla.org/security/announce/2011/mfsa2011-02.html
3) http://www.mozilla.org/security/announce/2011/mfsa2011-03.html
4) http://www.mozilla.org/security/announce/2011/mfsa2011-04.html
5) http://www.mozilla.org/security/announce/2011/mfsa2011-05.html
6) http://www.mozilla.org/security/announce/2011/mfsa2011-06.html
7) http://www.mozilla.org/security/announce/2011/mfsa2011-07.html
8) http://www.mozilla.org/security/announce/2011/mfsa2011-08.html
9) http://www.mozilla.org/security/announce/2011/mfsa2011-09.html
10) http://www.mozilla.org/security/announce/2011/mfsa2011-10.html

ZDI:
http://www.zerodayinitiative.com/advisories/ZDI-11-103/

Deep Links
Links available in Customer Area