Security researcher Nils reported a potentially exploitable use-after-free in an early test version of Firefox 25. Mozilla developer Bobby Holley found that the cause was an older garbage collection bug that a more recent change made easier to trigger. External Reference: http://www.mozilla.org/security/announce/2013/mfsa2013-92.html Acknowledgements: Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Nils as the original reporter. Statement: This issue does not affect the version of firefox and thunderbird as shipped with Red Hat Enterprise Linux 5 and 6