Ubuntu Security Notice 4599-3 – USN-4599-1 and USN-4599-2 fixed vulnerabilities in Firefox. The updates introduced various minor regressions. This update fixes the problem. Multiple security issues were discovered 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, spoof the prompt for opening an external application, obtain sensitive information, or execute arbitrary code. Various other issues were also addressed.