Vulnerability Details CVE-2026-6957
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
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 16.6%
CVSS Severity
CVSS v3 Score 8.0
References
Products affected by CVE-2026-6957
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cpe:2.3:a:mattermost:legal_hold:*