Medium 6.5Published Sep 15, 2025

CVE-2025-9076Mattermost Server exposes sensitive user credentials during shared channel membership synchronization

Updated under an hour ago (Oct 26, 2026, 3:40 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-862
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: Sep 15, 2025
First seen by InfoSec Signals: Oct 19, 2026

Affected products

Affected products

Mattermost Mattermost mattermost:mattermost (from the name)	from 10.10.0 through 10.10.1; 10.11.0 not affected; 10.10.2 not affected	CNA record
mattermost mattermost_server mattermost:mattermost_server	from 10.10.0 before 10.10.2	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.