# CVE-2026-56721: CamaleonCMS 2.9.2 Privilege Escalation via Parameter Confusion in UsersController

> Authenticated low-privileged users can escalate privileges and take over the site by exploiting parameter confusion to overwrite administrator credentials.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 Aug 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-m39h-f7fw-54qw

## What is CVE-2026-56721?

CVE-2026-56721 is a high-severity vulnerability in owen2345 CamaleonCMS, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

CamaleonCMS version 2.9.2 and earlier contains a privilege escalation vulnerability via insecure direct object reference (IDOR) that allows authenticated low-privileged attackers to overwrite any user's credentials by exploiting a parameter confusion flaw between the authorization filter and action body in the UsersController. Attackers can send a PATCH request to the updated_ajax endpoint setting params[:id] to their own user ID to pass the self-authorization check while simultaneously setting params[:user_id] to a victim's ID, causing the controller to load and mutate the victim's account, including overwriting administrator passwords to achieve full site takeover.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-56721?


## How do I fix CVE-2026-56721?

No fix has been published for CVE-2026-56721 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-56721 being exploited?

There is no known exploitation of CVE-2026-56721 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56721 and fix it if it is affected.

What it is: CVE-2026-56721 is a high-severity vulnerability in owen2345 CamaleonCMS, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-56721 in the wild and no public exploit code.

Affected product: owen2345 CamaleonCMS. 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-2026-56721/ (Markdown: https://insights.sbomify.com/CVE-2026-56721/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56721
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56721
- OSV: https://osv.dev/vulnerability/CVE-2026-56721

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56721/
Summaries are generated and may contain mistakes; the official description above is the record.