Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Published: 2026-07-08
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Fri, 10 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-606
References
Metrics threat_severity

None

threat_severity

Moderate


Wed, 08 Jul 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 08 Jul 2026 19:15:00 +0000

Type Values Removed Values Added
First Time appeared Lepture
Lepture mistune
Vendors & Products Lepture
Lepture mistune

Wed, 08 Jul 2026 17:00:00 +0000

Type Values Removed Values Added
Description Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Title Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions
Weaknesses CWE-1333
CWE-407
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-08T19:40:43.968Z

Reserved: 2026-07-07T18:20:06.126Z

Link: CVE-2026-59928

cve-icon Vulnrichment

Updated: 2026-07-08T17:45:57.618Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-07-08T16:23:21Z

Links: CVE-2026-59928 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-16T21:30:06Z

Weaknesses