CVE-2025-9076

Mattermost Server exposes sensitive user credentials during shared channel membership synchronization

CVSS 6.5 MEDIUMEPSS 0.2%CWE-862

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 6.5EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

15 Sep 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates