CVE-2025-11777

Cross-team channel membership access

CVSS 3.1 LOWEPSS 0.2%CWE-863

Vexday Risk Score

8Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 3.1EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

13 Nov 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates