CVE-2026-86349 — Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting

CVE-2026-86349

Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting PUBLISHED

Description (CNA)

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

Affected (CNA)

Vendor / product	Versions
Mattermost / Mattermost	affected 11.9.0 through 11.9.0; affected 11.8.0 through 11.8.4; affected 11.7.0 through 11.7.8; affected 10.11.0 through 10.11.22; unaffected 11.10.0; unaffected 11.9.1; unaffected 11.8.5; unaffected 11.7.9; unaffected 10.11.23

CWE

CWE-407

References

https://mattermost.com/security-updates

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.