CVE-2016-5254: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 3% chance of exploitation in the next 30 days.

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.

Affected products

• Mozilla Firefox: up to and including 47.0.1; version 45.1.0 only; version 45.1.1 only; version 45.2.0 only; version 45.3.0 only
• Oracle Linux: version 5.0 only; version 6 only; version 7 only

Published 2016-08-05. Last modified 2026-06-17.