CVE-2026-59929
MEDIUMMistune renderers/html.safe_url: HARMFUL_PROTOCOLS list misses legacy and chained schemes that historically chain to `javascript:` execution
Title source: cnaDescription
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.
References (3)
Core 3
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/lepture/mistune/security/advisories/GHSA-qfrw-5rxm-mhh2
X_Refsource_Misc x_refsource_misc
https://github.com/lepture/mistune/commit/c7101fcbb6e8790e8e39157c5ca2238fc6dd6cbc
X_Refsource_Misc x_refsource_misc
https://github.com/lepture/mistune/releases/tag/v3.3.0
Scores
CVSS v3
6.1
EPSS
0.0022
EPSS Percentile
13.3%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-184
CWE-79
Status
published
Products (3)
lepture/mistune
< 3.3.0
mistune_project/mistune
< 3.3.0
pypi/mistune
0 - 3.3.0PyPI
Published
Jul 08, 2026
Tracked Since
Jul 08, 2026