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CVE-2026-6957 Details

Description

Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:4.9 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

CNA: [email protected]CVSS-B:8 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://mattermost.com/security-updates	[email protected]	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-22	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')	[email protected]

Affected Products

Product	Versions
mattermost legal hold	<= 1.1.5
CPE cpe:2.3:a:mattermost:legal_hold::::::mattermost::* Remediation No remediation found in references.

Change History

4 change records found show changes

Date	Action	Recorded By
Jun 17, 2026	CVE Modified	[email protected]
Jun 17, 2026	CVE Modified	CISA-ADP
Jun 2, 2026	Initial Analysis	[email protected]
May 27, 2026	New CVE Received	[email protected]