# CVE-2026-9699: Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors

> Attackers with log access can obtain OpenAI API keys due to unsanitized error logging in the Mattermost Agents plugin.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Jun 2026
- **Updated:** 26 Jun 2026
- **Also known as:** GHSA-gr4w-63r3-8h38

## What is CVE-2026-9699?

CVE-2026-9699 is a medium-severity vulnerability in Mattermost, published on 26 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Mattermost Plugins versions <=11.6 10.18.11 11.3.6 11.6.5.0 fail to sanitize error responses from the OpenAI API before logging, which allows a user with access to server logs or support packets to obtain a valid or partially reconstructable OpenAI API key via inspection of mattermost.log entries generated during authentication failures. Mattermost Advisory ID: MMSA-2026-00609

Weakness: CWE-532 (Insertion of Sensitive Information into Log File)

## Which versions are affected by CVE-2026-9699?


## How do I fix CVE-2026-9699?

No fix has been published for CVE-2026-9699 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-9699 being exploited?

There is no known exploitation of CVE-2026-9699 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9699 and fix it if it is affected.

What it is: CVE-2026-9699 is a medium-severity vulnerability in Mattermost, published on 26 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-9699 in the wild and no public exploit code.

Affected product: Mattermost. 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-2026-9699/ (Markdown: https://insights.sbomify.com/CVE-2026-9699/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9699
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9699
- OSV: https://osv.dev/vulnerability/CVE-2026-9699

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9699/
Summaries are generated and may contain mistakes; the official description above is the record.