PT-2026-56508 · Lepture · Mistune

Published 2026-07-08 · Updated 2026-07-08 · CVE-2026-59922

NVD

CVSS v3.1

7.5

High

Base vector

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

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.

Fix

DoS

Weakness Enumeration

CWE-1333

CWE-407

Related Identifiers

CVE-2026-59922

Affected Products

Mistune

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-59922 · Security Note
• https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq · Note
• https://github.com/lepture/mistune/commit/96d0f57f8fe9eeb06bb4cff521962a27d7c402e7 · Note
• https://github.com/lepture/mistune/releases/tag/v3.3.0 · Note