CVE-2026-6957 HIGH

CVE-2026-6957: Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.

Vendor Mattermost
Product Mattermost
Weakness CWE-22 · Path traversal
Published May 27, 2026
Last update May 28, 2026
View on NVD All CVEs

CVSS base score

8.0/10
Attack vector Network
Attack complexity High
Privileges required High
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

What the vulnerability does

01Description

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

Key dates

02Disclosure timeline

May 27, 2026 CVE published
May 28, 2026 Record updated