CVE-2026-81920 Cross-site request forgery in Concrete CMS

Low 2.3 Published 15 Sep 2026 Updated 15 Sep 2026

An attacker can trick an authenticated admin into resetting SEO excluded words, altering URL slug generation policies.

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: None listed

What is CVE-2026-81920?

CVE-2026-81920 is a low-severity vulnerability in Concretecms Concrete Cms, published on 15 Sep 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

Concrete CMS below 9.5.3 was vulnerable to Cross-Site Request Forgery in the dashboard SEO Excluded Words page. The reset() controller action cleared the administrator-configured reserved-word list (concrete.seo.exclude_words) but did not validate the anti-CSRF token that the reset modal emitted, and it did not restrict the request to the POST method. A remote attacker who lured an authenticated user with SEO access to a crafted page could revert the reserved-word list to its default and silently alter future URL-slug generation for pages, files, topics, and other objects created through the Text urlify service, undoing the site's configured SEO slug policy. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Weakness: CWE-352

Which versions are affected by CVE-2026-81920?

It affects 1 product.

Products include Concretecms Concrete Cms.

How do I fix CVE-2026-81920?

No fix has been published for CVE-2026-81920 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-81920 being exploited?

There is no known exploitation of CVE-2026-81920 in the wild and no public exploit code.

All Concretecms Concrete Cms vulnerabilities

Sources

Also known as GHSA-5fv5-37wq-24h2.