CVE-2016-5254

Use-after-free vulnerability in the nsXULPopupManager::KeyDown function in Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 allows attackers to execute arbitrary code or cause a denial of service (heap memory corruption and application crash) by leveraging keyboard access to use the Alt key during selection of top-level menu items.

Source: CVE-2016-5254