CVE-2026-34721 Zammad has Cross-site request forgery (CSRF) in OAuth callback endpoints

Medium 5.9 Published 8 Apr 2026 Updated 9 Apr 2026

Attackers can exploit missing CSRF validation in OAuth callbacks to hijack user accounts in Zammad helpdesk systems.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-34721?

CVE-2026-34721 is a medium-severity vulnerability in Zammad Zammad, published on 8 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the OAuth callback endpoints for Microsoft, Google, and Facebook external credentials do not validate a CSRF state parameter. This vulnerability is fixed in 7.0.1 and 6.5.4.

Weakness: CWE-352

Which versions are affected by CVE-2026-34721?

It affects 1 product.

Products include Zammad Zammad.

How do I fix CVE-2026-34721?

No fix has been published for CVE-2026-34721 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-34721 being exploited?

There is no known exploitation of CVE-2026-34721 in the wild and no public exploit code.

All Zammad Zammad vulnerabilities

Sources

Also known as GHSA-mfwp-hx66-626c.