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

> CVE-2025-9076: Mattermost Server exposes sensitive user credentials during shared channel membership synchronization. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2025-9076
Last updated: 2026-10-19T17:10:00Z

- Published: 2025-09-15 10:06 UTC · Updated: 2026-10-19 17:10 UTC · Assigner: Mattermost
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
- EPSS: 0.26%, 18th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-862

## Description

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.

## Affected vendors and products

- Mattermost: Mattermost

## Tracked companies

- [Mattermost](https://rewindex.com/company/mattermost.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2025-9076)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2025-9076)
- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2025-9076 · Markdown: https://rewindex.com/cve/CVE-2025-9076.md · JSON: https://rewindex.com/api/v1/cves/CVE-2025-9076 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:03.973Z