Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8epss 0.3%
exploitation probability
0.3%top 78% of all CVEs
observed exploitation
nono source reports it
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 · MattermostReferences
https://mattermost.com/security-updates