CVE-2025-11776 Guest user can discover archived public channels
Guest users can discover archived public channels due to improper access control in the search API, exposing channel metadata.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-11776?
CVE-2025-11776 is a medium-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 14 Nov 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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
Weakness: CWE-863
Which versions are affected by CVE-2025-11776?
16 open source packages ship an affected version, including github.com/mattermost/mattermost-server, github.com/mattermost/mattermost and github.com/mattermost/mattermost-server/v5. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/mattermost/mattermost-server Go | All versions | None |
github.com/mattermost/mattermost-server Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost-server Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost Go | All versions | None |
github.com/mattermost/mattermost Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
10 more packages
github.com/mattermost/mattermost-server/v5 Go | All versions | None |
github.com/mattermost/mattermost-server/v5 Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost-server/v5 Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost-server/v6 Go | All versions | None |
github.com/mattermost/mattermost-server/v6 Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost-server/v6 Go | All versions | 5.3.2-0.20250815165020-c8d66301415d |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250815165020-c8d66301415d |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250815165020-c8d66301415d |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250815165020-c8d66301415d |
github.com/mattermost/mattermost/v5 Go | All versions | None |
Products include Mattermost Mattermost Server.
How do I fix CVE-2025-11776?
Upgrade github.com/mattermost/mattermost-server to 5.3.2-0.20250815165020-c8d66301415d or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2025-11776 being exploited?
There is no known exploitation of CVE-2025-11776 in the wild and no public exploit code.
Other vulnerabilities in Mattermost Mattermost Server
- CVE-2025-12419 Account takeover on OAuth/OpenID-enabled servers
- CVE-2025-12421 Account Takeover via Code Exchange Endpoint
- CVE-2025-4981 Path Traversal Leading to RCE by Any Authenticated Mattermost User
- CVE-2025-20051 Arbitrary file read via block duplication in Mattermost Boards
- CVE-2025-25279 Arbitrary file read in Mattermost Boards via import & export board archive
Sources
Also known as GHSA-j6gg-r5jc-47cm, GO-2025-4126, MINI-59fr-w6rm-38g7.