Vulnerability Details CVE-2026-6342
Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID: MMSA-2026-00601
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 9.4%
CVSS Severity
CVSS v3 Score 4.3
References
Products affected by CVE-2026-6342
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cpe:2.3:a:mattermost:mattermost_server:*
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cpe:2.3:a:mattermost:mattermost_server:11.1.0
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cpe:2.3:a:mattermost:mattermost_server:11.1.1
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cpe:2.3:a:mattermost:mattermost_server:11.1.2
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cpe:2.3:a:mattermost:mattermost_server:11.1.3
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cpe:2.3:a:mattermost:mattermost_server:11.3.0
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cpe:2.3:a:mattermost:mattermost_server:11.3.1
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cpe:2.3:a:mattermost:mattermost_server:11.3.2
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cpe:2.3:a:mattermost:mattermost_server:11.3.3