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

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

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **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:** No
- **Published:** 19 Feb 2026
- **Updated:** 9 Mar 2026
- **Also known as:** GHSA-9636-r3rx-jw83

## 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 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-2736?

It affects 1 product.


Products: 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.

## Is CVE-2026-2736 being exploited?

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

## Other vulnerabilities in Alkacon OpenCms

- [CVE-2018-8811](https://insights.sbomify.com/CVE-2018-8811/): Cross-site request forgery in n/a (high 8.8)
- [CVE-2019-11819](https://insights.sbomify.com/CVE-2019-11819/): Alkacon OpenCMS CSV Injection via New User module (high 7.8)
- [CVE-2005-4475](https://insights.sbomify.com/CVE-2005-4475/): Cross-site scripting in n/a (medium 6.8)
- [CVE-2024-42699](https://insights.sbomify.com/CVE-2024-42699/): OpenCMS Cross-Site Scripting vulnerability (medium 6.5)
- [CVE-2021-3312](https://insights.sbomify.com/CVE-2021-3312/): XML External Entity Reference in org.opencms:opencms-core (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-2736 and fix it if it is affected.

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

Affected product: Alkacon OpenCms. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-2736/ (Markdown: https://insights.sbomify.com/CVE-2026-2736/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-2736
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2736
- OSV: https://osv.dev/vulnerability/CVE-2026-2736

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-2736/
Summaries are generated and may contain mistakes; the official description above is the record.