VULNERABILITY INTELLIGENCE
CVE-2026-5751
CVSS score6.1 MEDIUM
EPSS probability0.26%
CISA KEVNot currently listed
Published2026-08-23
Last modified2026-10-12
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Description
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.
Weakness classification
- disclosure@vulncheck.com: CWE-79