CVE-2025-49222

Mattermost Shared Channel Upload Type Validation Bypass

Published Aug 21, 2025 CVSS 3.1 · 6.8 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

Update Mattermost to versions 10.11.0, 10.8.4, 10.5.9, 9.11.18, 10.9.3, 10.10.1 or higher.

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-25418 Mattermost Fails to Validate Remote Cluster Upload Sessions
Github GHSA Github GHSA GHSA-q453-638c-h4mr Mattermost Fails to Validate Remote Cluster Upload Sessions
References
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
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.
Title Mattermost Shared Channel Upload Type Validation Bypass
Weaknesses CWE-434
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Aug 21, 2025, 1:57 PM
Reserved
Jul 22, 2025, 7:46 AM
Status
Analyzed
Published
Aug 21, 2025, 8:15 AM
Modified
Jun 17, 2026, 9:30 AM