Bug 2498464

Summary: CVE-2026-59923 python-mistune08: Mistune: Arbitrary code execution through crafted Markdown links [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Matteo Signorini <msignori>
Component: python-mistune08Assignee: Michel Lind <michel>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: epel10CC: epel-packagers-sig, michel, neil, python-packagers-sig
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["32628229-32fa-4fad-a577-bda2933c8954"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2498142    

Description Matteo Signorini 2026-07-09 11:01:16 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.