PT-2026-56518 · Pypi · Mistune

Published 2026-07-08 · Updated 2026-07-08 · CVE-2026-59927

Positive Technologies (AI Summary)

CVSS v3.1

5.3

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Mistune versions prior to 3.3.0

Description The Include directive in src/mistune/directives/include.py only detects direct self-includes and fails to identify indirect cycles. This allows two markdown files that include each other to trigger unbounded recursion, resulting in a RecursionError and crashing the rendering request.

Recommendations Update to version 3.3.0.

Fix

Improper Handling of Exceptional Conditions

Uncontrolled Recursion

Weakness Enumeration

CWE-755

CWE-674

Related Identifiers

CVE-2026-59927

Affected Products

Mistune

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-59927 · Security Note
• https://github.com/lepture/mistune/releases/tag/v3.3.0 · Note
• https://github.com/lepture/mistune/commit/1bef343ade163fc3bb95572b15be720084cdb993 · Note
• https://github.com/lepture/mistune/security/advisories/GHSA-8mpj-m6qm-5qr8 · Note
• https://twitter.com/infoflowcloud/status/2074933021493387594 · Twitter Post
• https://twitter.com/CVEnew/status/2074931619438149743 · Twitter Post