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 0.003
EPSS Ranking 21.3%
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:0.1.0
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cpe:2.3:a:mattermost:legal_hold:0.2.0
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cpe:2.3:a:mattermost:legal_hold:0.3.0
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cpe:2.3:a:mattermost:legal_hold:0.3.1
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cpe:2.3:a:mattermost:legal_hold:0.3.2
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cpe:2.3:a:mattermost:legal_hold:0.3.3
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cpe:2.3:a:mattermost:legal_hold:0.3.4
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cpe:2.3:a:mattermost:legal_hold:0.4.0
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cpe:2.3:a:mattermost:legal_hold:0.4.1
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cpe:2.3:a:mattermost:legal_hold:0.4.2
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cpe:2.3:a:mattermost:legal_hold:0.4.3
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cpe:2.3:a:mattermost:legal_hold:0.5.0
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cpe:2.3:a:mattermost:legal_hold:1.0.0
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cpe:2.3:a:mattermost:legal_hold:1.0.1
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cpe:2.3:a:mattermost:legal_hold:1.0.2
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cpe:2.3:a:mattermost:legal_hold:1.1.0
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cpe:2.3:a:mattermost:legal_hold:1.1.1
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cpe:2.3:a:mattermost:legal_hold:1.1.2
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cpe:2.3:a:mattermost:legal_hold:1.1.3
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cpe:2.3:a:mattermost:legal_hold:1.1.4
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cpe:2.3:a:mattermost:legal_hold:1.1.5