Skip to content
OpenAdvisories
Medium · 6.1 CVE-2026-77088 EUVD-2026-64657GHSA-3r4x-v5v7-fm2rGHSA-jf6w-2mvx-633j

justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span

Published Aug 23, 2026 · Updated Aug 29, 2026 · Assigned by VulnCheck

Description

justhtml versions 0.9.0 through 1.21.0 contain a cross-site scripting vulnerability in to_markdown() where inline code spans fail to account for blank lines as block boundaries. Attackers can inject blank lines into code or pre element text to break the inline span, causing sanitized HTML to be emitted unescaped and re-parsed as live Markdown by compliant renderers.

Affected products

VendorProductAffectedFixed
EmilStenstrom justhtml 0.9.0 – ≤ 1.21.0 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI justhtml >= 0.9.0, < 1.22.0 1.22.0 GHSA-jf6w-2mvx-633j

References