CVE-2026-5389: Emilstenstrom Justhtml

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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

• Emilstenstrom Justhtml: before 1.13.0 (fixed in 1.13.0)

Published 2026-08-23. Last modified 2026-08-26.