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CVE PROGRAM SOURCE RECORD5.1 Medium

CVE-2026-5389

justhtml before 1.13.0 XSS via code fence breakout

Description

justhtml versions before 1.13.0 contain a cross-site scripting vulnerability in the to_markdown() function when serializing attacker-controlled pre content. Attackers can place backticks inside sanitized pre elements to break out of fixed-length code fences, allowing raw HTML to execute when the generated Markdown is rendered by CommonMark or GFM-style renderers.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

EmilStenstrom justhtml

Default version status: unaffected

  • 0 to < 1.13.0affected
  • 1.13.0unaffected
pkg:pypi/justhtml

References