CVE-2026-81913 Concrete CMS versions 9.5.0 through 9.5.2 are vulnerable to Open Redirect via the rcURL parameter.

Medium 5.3 Published 11 Sep 2026 Updated 11 Sep 2026

Attackers can redirect users to malicious sites after authentication via the rcURL parameter, facilitating phishing and credential theft.

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-2026-81913?

CVE-2026-81913 is a medium-severity vulnerability in Concretecms Concrete Cms, published on 11 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 versions 9.5.0 through 9.5.2 are vulnerable to Open Redirect via the rcURL parameter. An attacker can craft a single link on the site's own domain that sends a user to an arbitrary external site immediately after authentication, facilitating phishing and credential theft. The same handling is present in the registration flow, giving a second entry point on sites with registration enabled. Concrete CMS versions prior to 9.5.0 do not include the rcURL parameter or this allowlist and are not affected. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Michal M. for reporting.

Weakness: CWE-601

Which versions are affected by CVE-2026-81913?

It affects 1 product.

Products include Concretecms Concrete Cms.

How do I fix CVE-2026-81913?

No fix has been published for CVE-2026-81913 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-81913 being exploited?

There is no known exploitation of CVE-2026-81913 in the wild and no public exploit code.

All Concretecms Concrete Cms vulnerabilities

Sources

Also known as GHSA-jwgj-v3j4-f3wg.