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
References
History

Tue, 02 Jun 2026 14:30:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost legal Hold
CPEs cpe:2.3:a:mattermost:legal_hold:*:*:*:*:*:mattermost:*:*
Vendors & Products Mattermost legal Hold

Thu, 28 May 2026 04:45:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Wed, 27 May 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Wed, 27 May 2026 15:15:00 +0000

Type Values Removed Values Added
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
Title Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published: 2026-05-27T14:23:50.770Z

Updated: 2026-05-28T03:55:34.437Z

Reserved: 2026-04-24T13:23:50.185Z

Link: CVE-2026-6957

cve-icon Vulnrichment

Updated: 2026-05-27T17:26:56.583Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-27T15:16:34.903

Modified: 2026-06-02T14:29:03.550

Link: CVE-2026-6957

cve-icon Redhat

No data.