CVE-2026-59929 | THREATINT

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:, and res: to reach rendered href and src attributes and potentially execute script in affected user agents. This issue is fixed in version 3.3.0.

PUBLISHED Reserved 2026-07-07 | Published 2026-07-08 | Updated 2026-07-09 | Assigner GitHub_M

MEDIUM: 6.1CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Problem types

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-184: Incomplete List of Disallowed Inputs

Product status

< 3.3.0

affected

References

github.com/...istune/security/advisories/GHSA-qfrw-5rxm-mhh2

github.com/...ommit/c7101fcbb6e8790e8e39157c5ca2238fc6dd6cbc

github.com/lepture/mistune/releases/tag/v3.3.0

cve.org (CVE-2026-59929)

nvd.nist.gov (CVE-2026-59929)

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