Low 3.1Published Nov 13, 2025

CVE-2025-11777Cross-team channel membership access

Updated under an hour ago (Oct 28, 2026, 10:40 AM ET)

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It affects Mattermost and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Mattermost

Exploited in the last 30 days

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 LOW (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness (CWE): CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Mattermost
NVD analysis: Analyzed
Record last updated: Nov 13, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Mattermost Mattermost mattermost:mattermost (from the name)	from 10.11.0 through 10.11.3; from 10.5.0 through 10.5.11; 11.0.0 not affected; 10.11.4 not affected; 10.5.12 not affected	CNA record
mattermost mattermost_server mattermost:mattermost_server	from 10.5.0 before 10.5.12; from 10.11.0 before 10.11.4	NVD

References

References

https://mattermost.com/security-updates	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.