# CVE-2026-10106: Missing authorization in Mattermost

> Authenticated users can trigger interactive post actions in private channels they cannot access due to insufficient channel verification in action cookies.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **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-vvv9-9jm4-76jg, MINI-6gc6-926q-c4hg, MINI-q4gj-hq5q-g4mv

## What is CVE-2026-10106?

CVE-2026-10106 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 verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in that channel via a cookie obtained from any accessible channel.. Mattermost Advisory ID: MMSA-2026-00690

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-10106?

It affects 1 product.


Products: Mattermost Mattermost Server.

## How do I fix CVE-2026-10106?

Upgrade to a fixed version.

## Is CVE-2026-10106 being exploited?

There is no known exploitation of CVE-2026-10106 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-2026-10106 and fix it if it is affected.

What it is: CVE-2026-10106 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-2026-10106 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-2026-10106/ (Markdown: https://insights.sbomify.com/CVE-2026-10106/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10106
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10106
- OSV: https://osv.dev/vulnerability/CVE-2026-10106

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10106/
Summaries are generated and may contain mistakes; the official description above is the record.