Security researcher regenrecht reported via TippingPoint's Zero Day Initiative that a nsDOMAttribute node can be modified without informing the iterator object responsible for various DOM traversals. This flaw could lead to a inconsistent state where the iterator points to an object it believes is part of the DOM but actually points to some other object. If such an object had been deleted and its memory reclaimed by the system, then the iterator could be used to call into attacker-controlled memory.
This is now public: http://www.mozilla.org/security/announce/2010/mfsa2010-80.html
This issue has been addressed in following products: Red Hat Enterprise Linux 4 Red Hat Enterprise Linux 5 Red Hat Enterprise Linux 6 Via RHSA-2010:0966 https://rhn.redhat.com/errata/RHSA-2010-0966.html