Vulnerability Details CVE-2026-4054
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to validate the response body of proxied images, which allows a remote attacker to enact client-side DoS via an SVG file served from an attacker-controlled origin under a non-SVG Content-Type header (e.g. image/png) embedded in an og:image meta tag or Markdown image link.. Mattermost Advisory ID: MMSA-2026-00630
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 26.8%
CVSS Severity
CVSS v3 Score 4.3
References
Products affected by CVE-2026-4054
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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:10.11.11
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cpe:2.3:a:mattermost:mattermost_server:10.11.12
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cpe:2.3:a:mattermost:mattermost_server:10.11.13
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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:11.4.0
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cpe:2.3:a:mattermost:mattermost_server:11.4.1
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cpe:2.3:a:mattermost:mattermost_server:11.4.2
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cpe:2.3:a:mattermost:mattermost_server:11.4.3
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cpe:2.3:a:mattermost:mattermost_server:11.5.0
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cpe:2.3:a:mattermost:mattermost_server:11.5.1