Mozilla just released Firefox 3.0.8 that fixes two security issues.
Arbitrary code execution through XUL <tree> element
Security researcher Nils reported via TippingPoint’s Zero Day Initiative that the XUL tree method _moveToEdgeShift was in some cases triggering garbage collection routines on objects which were still in use. In such cases, the browser would crash when attempting to access a previously destroyed object and this crash could be used by an attacker to run arbitrary code on a victim’s computer.
This vulnerability was used by the reporter to win the 2009 CanSecWest Pwn2Own contest.
This vulnerability does not affect Firefox 2, Thunderbird 2, or released versions of SeaMonkey.
XSL Transformation vulnerability
Security researcher Guido Landi discovered that a XSL stylesheet could be used to crash the browser during a XSL transformation. An attacker could potentially use this crash to run arbitrary code on a victim’s computer.
This vulnerability was also previously reported as a stability problem by Ubuntu community member, Andre. Ubuntu community member Michael Rooney reported Andre’s findings to Mozilla, and Mozilla community member Martin helped reduce Andre’s original testcase and contributed a patch to fix the vulnerability.