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. Christian Holler, Jesse Ruderman, Eric Rahm, Robert Kaiser, Harald Kirschner, and Michael Henretty reported crash and memory safety problems that affect Firefox 42. External Reference: https://www.mozilla.org/security/announce/2015/mfsa2015-134.html Acknowledgements: Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Christian Holler, Jesse Ruderman, Eric Rahm, Robert Kaiser, Harald Kirschner, and Michael Henretty 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.