# CVE-2026-18115: Missing authorization in Concrete CMS

> Attackers with limited OAuth tokens can bypass field-level permissions to change other users' credentials, leading to account takeover.

- **Severity:** High 7.4 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-j7cg-26vv-9hjf

## What is CVE-2026-18115?

CVE-2026-18115 is a high-severity missing authorization vulnerability in Concrete CMS, published on 15 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Concrete CMS 9.2.0 to 9.5.2 did not enforce per-field edit_user_properties permissions on the REST API user write endpoints (PUT /ccm/api/1.0/users/{uID} and POST /ccm/api/1.0/users/{uID}/change_password). A user with an update-scoped OAuth token and permission to edit only one non-sensitive field could change another non-superuser's password, username, email, and attributes, taking over that account. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.4 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-18115?


## How do I fix CVE-2026-18115?

No fix has been published for CVE-2026-18115 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-18115 being exploited?

There is no known exploitation of CVE-2026-18115 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18115 and fix it if it is affected.

What it is: CVE-2026-18115 is a high-severity missing authorization vulnerability in Concrete CMS, published on 15 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-18115 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-2026-18115/ (Markdown: https://insights.sbomify.com/CVE-2026-18115/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18115
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18115
- OSV: https://osv.dev/vulnerability/CVE-2026-18115

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18115/
Summaries are generated and may contain mistakes; the official description above is the record.