Security researcher Sergey Glazunov reported a dangling pointer vulnerability in the implementation of navigator.plugins in which the navigator object could retain a pointer to the plugins array even after it had been destroyed. An attacker could potentially use this issue to crash the browser and run arbitrary code on a victim's computer.
This is now public: http://www.mozilla.org/security/announce/2010/mfsa2010-51.html
This issue has been addressed in following products: Red Hat Enterprise Linux 4 Red Hat Enterprise Linux 5 Via RHSA-2010:0682 https://rhn.redhat.com/errata/RHSA-2010-0682.html
This issue has been addressed in following products: Red Hat Enterprise Linux 4 Red Hat Enterprise Linux 5 Via RHSA-2010:0681 https://rhn.redhat.com/errata/RHSA-2010-0681.html
This issue has been addressed in following products: Red Hat Enterprise Linux 3 Red Hat Enterprise Linux 4 Via RHSA-2010:0680 https://rhn.redhat.com/errata/RHSA-2010-0680.html