CVE-2026-40082 Cacti: Session Fixation via missing session_regenerate_id() after login

Medium 5.4 Published 25 Jun 2026 Updated 26 Jun 2026

Attackers can hijack user sessions in Cacti due to missing session ID regeneration after login, allowing unauthorized access to victim accounts.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-40082?

CVE-2026-40082 is a medium-severity authentication bypass vulnerability in Cacti Cacti, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Cacti is an open source performance and fault management framework. Versions 1.2.30 and prior have missing session_regenerate_id() after login, leading to Session Fixation. session_regenerate_id() is NOT called after successful login. The login flow at auth_login.php:203-207 directly sets $_SESSION[SESS_USER_ID] without rotating the session ID. The session cookie configuration is otherwise good (httponly=true, samesite=Strict, secure=true for HTTPS at include/global.php:513-537), but these do not prevent session fixation via same-site vectors. This issue has been fixed in version 1.2.31.

Weakness: CWE-384

Which versions are affected by CVE-2026-40082?

It affects 1 product.

Products include Cacti Cacti.

How do I fix CVE-2026-40082?

Upgrade to a fixed version.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-40082 being exploited?

There is no known exploitation of CVE-2026-40082 in the wild and no public exploit code.

All Cacti Cacti vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-40082, GHSA-273r-qr93-wgcp, UBUNTU-CVE-2026-40082.