Vulnerability Details CVE-2025-20621
Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 48.7%
CVSS Severity
CVSS v3 Score 6.5
References
Products affected by CVE-2025-20621
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cpe:2.3:a:mattermost:mattermost_server:10.0.0
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cpe:2.3:a:mattermost:mattermost_server:10.0.1
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cpe:2.3:a:mattermost:mattermost_server:10.0.2
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cpe:2.3:a:mattermost:mattermost_server:10.0.3
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cpe:2.3:a:mattermost:mattermost_server:10.1.0
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cpe:2.3:a:mattermost:mattermost_server:10.1.1
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cpe:2.3:a:mattermost:mattermost_server:10.1.2
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cpe:2.3:a:mattermost:mattermost_server:10.1.3
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cpe:2.3:a:mattermost:mattermost_server:10.2.0
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cpe:2.3:a:mattermost:mattermost_server:9.11.0
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cpe:2.3:a:mattermost:mattermost_server:9.11.1
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cpe:2.3:a:mattermost:mattermost_server:9.11.2
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cpe:2.3:a:mattermost:mattermost_server:9.11.3
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cpe:2.3:a:mattermost:mattermost_server:9.11.4
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cpe:2.3:a:mattermost:mattermost_server:9.11.5