CVE-2026-86349 — Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting
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 …
Published: 2026-09-14 · CVSS: 4.3 · CVSS 3.1
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
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7