Mattermost Incorrect Authorization vulnerability
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API, which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint.
This issue can be reached over the network, attack complexity is high, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.
The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
CVE-2025-11777 is classified as CWE-863: Incorrect Authorization. An authorisation check runs but reaches the wrong conclusion, permitting actions it should refuse.
CVE-2025-11777 is recorded against 7 packages.
Published on 17 November 2025 and last revised on 3 March 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.
github.com (Advisory)
github.com (Fix)
github.com (Fix)
github.com (Fix)
mattermost.com (Web)
github.com/mattermost/mattermost has other advisories on record. If you are patching this one, these are worth checking on the same host:
These advisories are the same class of weakness (CWE-863: Incorrect Authorization) in other software:
Details
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| github.com/mattermost/mattermost | — | — |
| github.com/mattermost/mattermost-server | — | — |
| github.com/mattermost/mattermost-server/v5 | — | — |
| github.com/mattermost/mattermost-server/v6 | — | — |
| github.com/mattermost/mattermost/server/v8 | — | — |
| github.com/mattermost/mattermost/v5 | — | — |
| mattermost-server | 10.11.0 | 10.11.4 |
References
Similar Threats
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