Vulnerability Details CVE-2026-3115
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 6.8%
CVSS Severity
CVSS v3 Score 4.3
References
Products affected by CVE-2026-3115
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cpe:2.3:a:mattermost:mattermost_server:10.11.0
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cpe:2.3:a:mattermost:mattermost_server:10.11.1
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cpe:2.3:a:mattermost:mattermost_server:10.11.10
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cpe:2.3:a:mattermost:mattermost_server:10.11.2
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cpe:2.3:a:mattermost:mattermost_server:10.11.3
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cpe:2.3:a:mattermost:mattermost_server:10.11.4
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cpe:2.3:a:mattermost:mattermost_server:10.11.5
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cpe:2.3:a:mattermost:mattermost_server:10.11.6
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cpe:2.3:a:mattermost:mattermost_server:10.11.7
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cpe:2.3:a:mattermost:mattermost_server:10.11.8
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cpe:2.3:a:mattermost:mattermost_server:10.11.9
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cpe:2.3:a:mattermost:mattermost_server:11.2.0
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cpe:2.3:a:mattermost:mattermost_server:11.2.1
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cpe:2.3:a:mattermost:mattermost_server:11.2.2
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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:11.4.0