Ubuntu Security Notice 2936-3 – USN-2936-1 fixed vulnerabilities in Firefox. The update caused an issue where a device update POST request was sent every time about:preferences#sync was shown. This update fixes the problem. Christian Holler, Tyson Smith, Phil Ringalda, Gary Kwong, Jesse Ruderman, Mats Palmgren, Carsten Book, Boris Zbarsky, David Bolter, Randell Jesup, Andrew McCreight, and Steve Fink discovered multiple memory safety issues in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service via application crash, or execute arbitrary code with the privileges of the user invoking Firefox. An invalid write was discovered when using the JavaScript .watch() method in some circumstances. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code with the privileges of the user invoking Firefox. Various other issues were also addressed.