# CVE-2023-27266: Disclosure of team owner email address when when accessing the teams API

> Team admins can view the team owner's email address via the API, bypassing the ShowEmailAddress privacy setting.

- **Severity:** Low 2.7 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/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:** Yes
- **Published:** 27 Feb 2023
- **Updated:** 6 Dec 2024
- **Also known as:** BIT-mattermost-2023-27266, GHSA-cxwh-9cmm-77cp

## What is CVE-2023-27266?

CVE-2023-27266 is a low-severity vulnerability in Mattermost Mattermost Server, published on 27 Feb 2023. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Mattermost fails to honor the ShowEmailAddress setting when constructing a response to the /api/v4/users/me/teams  API endpoint, allowing an attacker with team admin privileges to learn the team owner's email address in the response.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2023-27266?

1 open source package ship an affected version, including mattermost. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mattermost` | Bitnami | From 5.12.0 | 7.7.0 |

Products: Mattermost Mattermost Server.

## How do I fix CVE-2023-27266?

Upgrade mattermost to 7.7.0 or later.

## Is CVE-2023-27266 being exploited?

There is no known exploitation of CVE-2023-27266 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-2023-27266 and fix it if it is affected.

What it is: CVE-2023-27266 is a low-severity vulnerability in Mattermost Mattermost Server, published on 27 Feb 2023. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-27266 in the wild and no public exploit code.

Affected packages and fixed versions:
- mattermost (Bitnami): affected from 5.12.0; fixed in 7.7.0

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-2023-27266/ (Markdown: https://insights.sbomify.com/CVE-2023-27266/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-27266
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-27266
- OSV: https://osv.dev/vulnerability/CVE-2023-27266

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-27266/
Summaries are generated and may contain mistakes; the official description above is the record.