# CVE-2026-91181: Data Retention Teams Endpoint Leaks Private Team Invite ID

> Authenticated users with read-only data retention permissions can leak private team invite IDs and emails, allowing unauthorized team access.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-w86c-vmwh-pppx, MINI-36q3-vq87-4v6r, MINI-8xmr-q683-3xm3

## What is CVE-2026-91181?

CVE-2026-91181 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 14 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 Fail to sanitize Team objects returned by the data retention teams endpoint which allows an authenticated user holding only the read-only Data Retention Policy permission to obtain a private team's secret invite_id and email, and use it to join the team without authorization, via GET /api/v4/data_retention/policies/{policy_id}/teams.. Mattermost Advisory ID: MMSA-2026-00702

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-91181?

It affects 1 product.


Products: Mattermost Mattermost Server.

## How do I fix CVE-2026-91181?

Apply the vendor's patch.

## Is CVE-2026-91181 being exploited?

There is no known exploitation of CVE-2026-91181 in the wild and no public exploit code.

## Other vulnerabilities in Mattermost Mattermost Server

- [CVE-2025-12419](https://insights.sbomify.com/CVE-2025-12419/): Account takeover on OAuth/OpenID-enabled servers (critical 9.9)
- [CVE-2025-12421](https://insights.sbomify.com/CVE-2025-12421/): Account Takeover via Code Exchange Endpoint (critical 9.9)
- [CVE-2025-4981](https://insights.sbomify.com/CVE-2025-4981/): Path Traversal Leading to RCE by Any Authenticated Mattermost User (critical 9.9)
- [CVE-2025-20051](https://insights.sbomify.com/CVE-2025-20051/): Arbitrary file read via block duplication in Mattermost Boards (critical 9.9)
- [CVE-2025-25279](https://insights.sbomify.com/CVE-2025-25279/): Arbitrary file read in Mattermost Boards via import & export board archive (critical 9.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91181 and fix it if it is affected.

What it is: CVE-2026-91181 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 14 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-91181 in the wild and no public exploit code.

Affected product: Mattermost Mattermost Server. 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-2026-91181/ (Markdown: https://insights.sbomify.com/CVE-2026-91181/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91181
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91181
- OSV: https://osv.dev/vulnerability/CVE-2026-91181

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91181/
Summaries are generated and may contain mistakes; the official description above is the record.