# CVE-2026-81908: Missing authorization in Concrete CMS

> Authenticated users can enumerate all site groups via the REST API, exposing organizational structure and roles.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/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 Sep 2026
- **Updated:** 11 Sep 2026
- **Also known as:** GHSA-865j-87f7-7r6w

## What is CVE-2026-81908?

CVE-2026-81908 is a medium-severity missing authorization vulnerability in Concrete CMS, published on 11 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Concrete CMS 9.2.0 to 9.5.2 contain a missing authorization vulnerability in the REST API Groups list endpoint. The listGroups() method in concrete/src/Api/Controller/Groups.php registers a permissions checker callback that unconditionally returns true, so no per-object (tree node) authorization is enforced when the group collection is returned. An authenticated user whose API token carries the groups:read scope can call GET /ccm/api/1.0/groups and receive every group on the site regardless of the view permissions on those groups, disclosing the organization's group structure, roles, and access hierarchy. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-81908?


## How do I fix CVE-2026-81908?

No fix has been published for CVE-2026-81908 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-81908 being exploited?

There is no known exploitation of CVE-2026-81908 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81908 and fix it if it is affected.

What it is: CVE-2026-81908 is a medium-severity missing authorization vulnerability in Concrete CMS, published on 11 Sep 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-2026-81908 in the wild and no public exploit code.

Affected product: Concrete CMS. 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-2026-81908/ (Markdown: https://insights.sbomify.com/CVE-2026-81908/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81908
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81908
- OSV: https://osv.dev/vulnerability/CVE-2026-81908

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81908/
Summaries are generated and may contain mistakes; the official description above is the record.