Use-after-free vulnerability in the MutationObserver::disconnect function in core/dom/MutationObserver.cpp in the DOM implementation in Blink, as used in Google Chrome before 42.0.2311.135, allows remote attackers to cause a denial of service or possibly have unspecified other impact by triggering an attempt to unregister a MutationObserver object that is not currently registered.
https://src.chromium.org/viewvc/blink?revision=192655&view=revision
https://security.gentoo.org/glsa/201506-04
https://code.google.com/p/chromium/issues/detail?id=453279
http://www.ubuntu.com/usn/USN-2582-1
http://www.securitytracker.com/id/1032234
http://www.securityfocus.com/bid/74389
http://www.debian.org/security/2015/dsa-3242
http://rhn.redhat.com/errata/RHSA-2015-0921.html
http://lists.opensuse.org/opensuse-updates/2015-05/msg00009.html
http://googlechromereleases.blogspot.com/2015/04/stable-channel-update_28.html