Mozilla developers and community identified and fixed several memory safety bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these bugs showed evidence of memory corruption under certain circumstances, and we presume that with enough effort at least some of these could be exploited to run arbitrary code. Tyson Smith, Bobby Holley, Chris Coulson, Byron Campen, and Eric Rahm reported memory safety problems and crashes that affect Firefox 39. External Reference: https://www.mozilla.org/security/announce/2015/mfsa2015-79.html Acknowledgements: Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Tyson Smith, Bobby Holley, Chris Coulson, Byron Campen, and Eric Rahm as the original reporter. Statement: This issue does not affect the version of firefox and thunderbird as shipped with Red Hat Enterprise Linux 5, 6 and 7.