Description
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
Published: 2026-09-14
Score: 4.3 Medium
EPSS: n/a
KEV: No
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

Vendor Solution

Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.9, 10.11.23 or higher.

Tracking

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Advisories

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References
Link Providers
https://mattermost.com/security-updates cve-icon
History

Mon, 14 Sep 2026 14:00:00 +0000

Type Values Removed Values Added
Description 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
Title Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting
Weaknesses CWE-407
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L'}

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-09-14T13:51:30.175Z

Reserved: 2026-09-07T09:38:22.768Z

Link: CVE-2026-86349

cve-icon Vulnrichment

No data.

cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses