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Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting

CVSS 3.1 4.3 MEDIUMCheck source for fixed versionsKEV status unknown

cve-program · CVE-2026-86349

Published

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.8, 10.11.x <= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707

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CVE-2026-86349 · CVE overview and exploitation status

cve-program · CVE-2026-86349

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ChangeIntel

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Sources read 13 Nov 16:22 UTC · 274 of 275 readable · 273 fully read · documentation 469/469 current