CVE-2026-2736 Reflected Cross-Site Scripting (XSS) vulnerability in Alkacon's OpenCms

Medium 5.1 Published 19 Feb 2026 Updated 9 Mar 2026

Reflected XSS in OpenCms allows attackers to execute JavaScript via malicious URLs, potentially stealing session cookies or impersonating users.

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-2026-2736?

CVE-2026-2736 is a medium-severity cross-site scripting vulnerability in Alkacon OpenCms, published on 19 Feb 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

Reflected Cross-site Scripting (XSS) in Alkacon's OpenCms v18.0, which allows an attacker to execute JavaScript code in the victim's browser by sending the victim a malicious URL containing the ‘q’ parameter in ‘/search/index.html’. This vulnerability can be exploited to steal sensitive user information such as session cookies, or to perform actions while impersonating the user.

Weakness: CWE-79

Which versions are affected by CVE-2026-2736?

It affects 1 product.

Products include Alkacon Opencms.

How do I fix CVE-2026-2736?

No fix has been published for CVE-2026-2736 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-2736 being exploited?

There is no known exploitation of CVE-2026-2736 in the wild and no public exploit code.

Sources

Also known as GHSA-9636-r3rx-jw83.