# CVE-2025-49222: Mattermost Shared Channel Upload Type Validation Bypass

> CVE-2025-49222: Mattermost Shared Channel Upload Type Validation Bypass. CVSS 6.8 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2025-49222
Last updated: 2026-06-17T09:30:56Z

- Published: 2025-08-21 07:59 UTC · Updated: 2026-06-17 09:30 UTC · Assigner: Mattermost
- CVSS: 6.8 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N
- EPSS: 0.30%, 23th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-434

## Description

Mattermost versions 10.8.x \<= 10.8.3, 10.5.x \<= 10.5.8, 9.11.x \<= 9.11.17, 10.9.x \<= 10.9.2, 10.10.x \<= 10.10.0 fail to validate upload types in remote cluster upload sessions which allows a system admin to upload non-attachment file types via shared channels that could potentially be placed in arbitrary filesystem directories.

## 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-2025-49222)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2025-49222)
- [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-2025-49222 · Markdown: https://rewindex.com/cve/CVE-2025-49222.md · JSON: https://rewindex.com/api/v1/cves/CVE-2025-49222 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:15:29.601Z