CVE-2026-5751Medium· 6.1▾ Sunlitjusthtml versions 1.13.0 and earlier contain a parser-differential / mutation cross-site scripting (mXSS) vulnerability when using a custom SanitizationPolicy that preserves foreign namespaces (e.g., drop_foreign_namespaces=False with al…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 33.6 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Aug 24.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.2%
0.2% → 0.3%
Last analysed / modified upstream
— → 6.1
low → medium
justhtml versions 1.13.0 and earlier contain a parser-differential / mutation cross-site scripting (mXSS) vulnerability when using a custom SanitizationPolicy that preserves foreign namespaces (e.g., drop_foreign_namespaces=False with allowlisted SVG/MathML elements or raw-text containers such as <style>). Specially crafted input can sanitize into markup that appears safe but becomes unsafe when re-parsed by a browser or another HTML parser, allowing markup injection. The default safe configuration (sanitize=True) is not affected. Fixed in 1.14.0.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
justhtml >= 1.13.0, < 1.14.0Patched in:
justhtml 1.14.0Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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CVE-2026-8445Critical· 9.8justhtml versions <= 1.11.0 (fixed in 1.12.0) do not sufficiently escape HTML-significant characters (angle brackets) in text nodes when converting a parsed document to Markdown via to_markdown()
CVE-2026-9769High· 7.5justhtml through 1.9.1 (fixed in 1.10.0) is vulnerable to uncontrolled recursion leading to denial of service
CVE-2026-4671High· 7.5justhtml before 1.18.0 contains multiple low-severity denial-of-service issues in CSS selector handling and linkification
CVE-2026-8630MediumJustHTML Affected by Mutation XSS via Literal Text Serialization in Raw Text Elements (style/script)