CVE-2025-12756 Insecure Direct Object Reference in Mattermost Boards Plugin Enables Unauthorised Comment Deletion
Authenticated editors can delete other users' comments in Mattermost Boards due to missing permission checks, requiring an upgrade to fix.
- 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-2025-12756?
CVE-2025-12756 is a medium-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 1 Dec 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to validate user permissions when deleting comments in Boards, which allows an authenticated user with the editor role to delete comments created by other users.
Weakness: CWE-863
Which versions are affected by CVE-2025-12756?
18 open source packages ship an affected version, including github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost and github.com/mattermost/mattermost-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/mattermost/mattermost/server/v8 Go | All versions | None |
github.com/mattermost/mattermost/server/v8 Go | All versions to 8.0.0-20251013062617-7977e7e6dae3 | None |
github.com/mattermost/mattermost/server/v8 Go | All versions to 8.0.0-20251013062617-7977e7e6dae3 | None |
github.com/mattermost/mattermost Go | All versions | None |
github.com/mattermost/mattermost Go | From 10.11.0 to 10.11.4 | None |
github.com/mattermost/mattermost Go | From 10.11.0 to 10.11.4 | None |
12 more packages
github.com/mattermost/mattermost Go | From 10.11.0+incompatible | None |
github.com/mattermost/mattermost Go | From 10.12.0 to 10.12.1 | None |
github.com/mattermost/mattermost Go | From 10.12.0 to 10.12.1 | None |
github.com/mattermost/mattermost Go | From 10.12.0+incompatible | None |
github.com/mattermost/mattermost Go | From 10.5.0 to 10.5.12 | None |
github.com/mattermost/mattermost Go | From 10.5.0 to 10.5.12 | None |
github.com/mattermost/mattermost Go | From 10.5.0+incompatible | None |
github.com/mattermost/mattermost Go | From 11.0.0 to 11.0.2 | None |
github.com/mattermost/mattermost Go | From 11.0.0 to 11.0.2 | None |
github.com/mattermost/mattermost-server Go | All versions | None |
github.com/mattermost/mattermost-server/v5 Go | All versions | None |
github.com/mattermost/mattermost-server/v6 Go | All versions | None |
Products include Mattermost Mattermost Server.
How do I fix CVE-2025-12756?
Upgrade to a fixed version.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2025-12756 being exploited?
There is no known exploitation of CVE-2025-12756 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-p6gj-jc38-x2m7, GO-2025-4172.