Security researcher Jukka Jylänki reported a use-after-free in JavaScript caused by how objects and pointers are handled during incremental garbage collection in some circumstances working with object groups. When triggered, this causes a potential exploitable crash but is mitigated by the difficulties in controlling the crash and its output. External Reference: https://www.mozilla.org/security/announce/2016/mfsa2016-71.html Acknowledgements: Name: the Mozilla project Upstream: Jukka Jylänki Statement: This issue does not affect the version of firefox and thunderbird as shipped with Red Hat Enterprise Linux 5, 6 and 7.