CVE-2021-3311: October CMS October

Critical severity, CVSS 9.8. EPSS: 2.9% chance of exploitation in the next 30 days.

An issue was discovered in October through build 471. It reactivates an old session ID (which had been invalid after a logout) once a new login occurs. NOTE: this violates the intended Auth/Manager.php authentication behavior but, admittedly, is only relevant if an old session ID is known to an attacker.

Affected products

• October CMS October: up to and including 1.0.471

Published 2021-02-05. Last modified 2026-06-17.