# CVE-2026-10085: Ordinary group/direct message member can enable group_constrained and remove all channel participants

> An ordinary member can remove all participants from a conversation by improperly setting the group_constrained flag, disrupting communication.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Jul 2026
- **Updated:** 13 Jul 2026
- **Also known as:** GHSA-6v2h-jj3h-8gmx, MINI-v7xq-33ww-pgmq, MINI-x72m-qxvh-4x4q

## What is CVE-2026-10085?

CVE-2026-10085 is a medium-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 13 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation via the channel patch API.. Mattermost Advisory ID: MMSA-2026-00688

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-10085?

It affects 1 product.


Products: Mattermost Mattermost Server.

## How do I fix CVE-2026-10085?

Apply the vendor's patch.

## Is CVE-2026-10085 being exploited?

There is no known exploitation of CVE-2026-10085 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-2026-10085 and fix it if it is affected.

What it is: CVE-2026-10085 is a medium-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 13 Jul 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-2026-10085 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-2026-10085/ (Markdown: https://insights.sbomify.com/CVE-2026-10085/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10085
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10085
- OSV: https://osv.dev/vulnerability/CVE-2026-10085

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10085/
Summaries are generated and may contain mistakes; the official description above is the record.