CVE-2025-10545

Guest user can add unauthorized team users to private channels

CVSS 3.1 LOWEPSS 0.3%CWE-863

Vexday Risk Score

8Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 3.1EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

16 Oct 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the `/api/v4/channels/{channel_id}/members` 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