# 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. - **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 1 Dec 2025 - **Updated:** 1 Dec 2025 - **Also known as:** GHSA-p6gj-jc38-x2m7, GO-2025-4172 ## 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 (Incorrect Authorization) ## 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 | Ecosystem | 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 | | `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: Mattermost Mattermost Server. ## How do I fix CVE-2025-12756? Upgrade to a fixed version. ## 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](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-2025-12756 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2025-12756 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/mattermost/mattermost/server/v8 (Go): affected all versions; no fix listed - github.com/mattermost/mattermost/server/v8 (Go): affected all versions up to 8.0.0-20251013062617-7977e7e6dae3; no fix listed - github.com/mattermost/mattermost/server/v8 (Go): affected all versions up to 8.0.0-20251013062617-7977e7e6dae3; no fix listed - github.com/mattermost/mattermost (Go): affected all versions; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.11.0 up to 10.11.4; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.11.0 up to 10.11.4; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.11.0+incompatible; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.12.0 up to 10.12.1; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.12.0 up to 10.12.1; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.12.0+incompatible; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.5.0 up to 10.5.12; no fix listed - github.com/mattermost/mattermost (Go): affected from 10.5.0 up to 10.5.12; no fix listed 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-2025-12756/ (Markdown: https://insights.sbomify.com/CVE-2025-12756/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-12756 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-12756 - OSV: https://osv.dev/vulnerability/CVE-2025-12756 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-12756/ Summaries are generated and may contain mistakes; the official description above is the record.