CVE-2026-6957CWE-22

Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.

High · published May 27, 2026

CVSS v3.1
8.0
EPSS
0%
Percentile
39.0
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
8.0 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00461 · 39.0th percentile
Weakness
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Published
2026-05-27T14:23Z
EPSS history
Timeline
  • 27 MAY 14:23Z
    Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.
    cvelistv5