CVE-2026-6957

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

CVSS 8 HIGHEPSS 0.3%CWE-22

Vexday Risk Score

21Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 8EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

27 May 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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

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

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates