CVE-2016-5261: Mozilla Firefox

High severity, CVSS 8.8. EPSS: 4.2% chance of exploitation in the next 30 days.

Integer overflow in the WebSocketChannel class in the WebSockets subsystem in Mozilla Firefox before 48.0 and Firefox ESR < 45.4 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted packets that trigger incorrect buffer-resize operations during buffering.

Affected products

• Mozilla Firefox: up to and including 47.0.1

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