Mistune directives/include: mutual `.. include::` recursion crashes the renderer with `RecursionError`, denial of service via two attacker-controlled markdown files

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Summary

CVECVE-2026-59927
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-08 17:17:28 UTC
Updated2026-07-09 19:30:14 UTC
DescriptionMistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.003070000 probability, percentile 0.225540000 (date 2026-07-10)

Problem Types: CWE-674 | CWE-755 | CWE-674 CWE-674: Uncontrolled Recursion | CWE-755 CWE-755: Improper Handling of Exceptional Conditions

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mistune Project Mistune All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Lepture Mistune affected < 3.3.0 Not specified

References

ReferenceSourceLinkTags
github.com/lepture/mistune/security/advisories/GHSA-8mpj-m6qm-5qr8 [email protected] github.com Exploit, Third Party Advisory
github.com/lepture/mistune/commit/1bef343ade163fc3bb95572b15be720084cdb993 [email protected] github.com Patch
github.com/lepture/mistune/releases/tag/v3.3.0 [email protected] github.com Release Notes
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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