CVE-2016-4423: Debian Linux

High severity, CVSS 7.5. EPSS: 1.9% chance of exploitation in the next 30 days.

The attemptAuthentication function in Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php in Symfony before 2.3.41, 2.7.x before 2.7.13, 2.8.x before 2.8.6, and 3.0.x before 3.0.6 does not limit the length of a username stored in a session, which allows remote attackers to cause a denial of service (session storage consumption) via a series of authentication attempts with long, non-existent usernames.

Affected products

• Debian Debian Linux: version 8.0 only
• Sensiolabs Symfony: up to and including 2.3.40; version 2.7.0 only; version 2.7.1 only; version 2.7.2 only; version 2.7.3 only; version 2.7.4 only; …

Published 2016-06-01. Last modified 2026-06-17.