Vulnerability Details CVE-2026-93849
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 Mattermost fail to apply allocation limits to the byte-string decode paths in its WebSocket msgpack decoder, which allows an authenticated remote attacker to cause excessive server memory allocation via a crafted binary WebSocket frame declaring a Bin32 payload length of up to 4,294,967,295 bytes.. Mattermost Advisory ID: MMSA-2026-00768
Exploit prediction scoring system (EPSS) score
EPSS Score 0.005
EPSS Ranking 39.7%
CVSS Severity
CVSS v3 Score 6.5
References
Products affected by CVE-2026-93849
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cpe:2.3:a:mattermost:mattermost_server:11.10.0
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cpe:2.3:a:mattermost:mattermost_server:11.10.1
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cpe:2.3:a:mattermost:mattermost_server:11.7.0
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cpe:2.3:a:mattermost:mattermost_server:11.7.1
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cpe:2.3:a:mattermost:mattermost_server:11.7.10
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cpe:2.3:a:mattermost:mattermost_server:11.7.2
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cpe:2.3:a:mattermost:mattermost_server:11.7.3
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cpe:2.3:a:mattermost:mattermost_server:11.7.4
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cpe:2.3:a:mattermost:mattermost_server:11.7.5
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cpe:2.3:a:mattermost:mattermost_server:11.7.6
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cpe:2.3:a:mattermost:mattermost_server:11.7.7
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cpe:2.3:a:mattermost:mattermost_server:11.7.8
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cpe:2.3:a:mattermost:mattermost_server:11.7.9
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cpe:2.3:a:mattermost:mattermost_server:11.8.0
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cpe:2.3:a:mattermost:mattermost_server:11.8.1
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cpe:2.3:a:mattermost:mattermost_server:11.8.2
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cpe:2.3:a:mattermost:mattermost_server:11.8.3
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cpe:2.3:a:mattermost:mattermost_server:11.8.4
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cpe:2.3:a:mattermost:mattermost_server:11.8.5
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cpe:2.3:a:mattermost:mattermost_server:11.9.0
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cpe:2.3:a:mattermost:mattermost_server:11.9.1