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 Details
- CVSS 3.1 Base Score: 4.9
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N)
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