CVE-2026-6827

justhtml before 1.17.0 contains multiple security issues in sanitization, serialization, and programmatic DOM handling. When custom policies preserve foreign namespaces SVG/MathML, dangerous content such as HTML integration points SVG , MathML and mutation-XSS parser-differential payloads could...

CVE-2026-5751

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., dropforeignnamespaces=False with allowlisted SVG/MathML elements or raw-text containers such as...

EUVD-2026-64655

justhtml before 1.17.0 contains multiple security issues in sanitization, serialization, and programmatic DOM handling. When custom policies preserve foreign namespaces SVG/MathML, dangerous content such as HTML integration points SVG , MathML and mutation-XSS parser-differential payloads could...

CVE-2026-6827 justhtml before 1.17.0 Multiple Cross-Site Scripting Vulnerabilities

justhtml before 1.17.0 contains multiple security issues in sanitization, serialization, and programmatic DOM handling. When custom policies preserve foreign namespaces SVG/MathML, dangerous content such as HTML integration points SVG , MathML and mutation-XSS parser-differential payloads could...

CVE-2026-5751

justhtml versions 1.13.0 and earlier are affected by a parser-differential / mutation XSS (mXSS) vulnerability. The issue occurs when a custom SanitizationPolicy preserves foreign namespaces (e.g., drop_foreign_namespaces=False with allowlisted SVG/MathML elements or raw-text containers such as )...

EUVD-2026-64654

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., dropforeignnamespaces=False with allowlisted SVG/MathML elements or raw-text containers such as...

CVE-2026-5751 justhtml before 1.14.0 Mutation XSS via custom sanitization policies

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., dropforeignnamespaces=False with allowlisted SVG/MathML elements or raw-text containers such as...

CVE-2026-5751 justhtml before 1.14.0 Mutation XSS via custom sanitization policies

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., dropforeignnamespaces=False with allowlisted SVG/MathML elements or raw-text containers such as...

CVE-2026-5751 justhtml before 1.14.0 Mutation XSS via custom sanitization policies

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., dropforeignnamespaces=False with allowlisted SVG/MathML elements or raw-text containers such as...

justhtml has sanitization bypass in custom policies and programmatic DOM

Summary justhtml 1.17.0 fixes multiple security issues in sanitization, serialization, and programmatic DOM handling. Most of these issues affected advanced or custom configurations rather than the default safe path. Affected versions - justhtml , MathML , SVG / , and MathML text integration poin...

PT-2026-79772

Name of the Vulnerable Software and Affected Versions justhtml versions prior to 1.17.0 Description Security issues exist in sanitization, serialization, and programmatic DOM handling. When custom policies preserve foreign namespaces like SVG or MathML, dangerous content such as HTML integration...

Multiple security fixes in justhtml

Summary justhtml 1.16.0 fixes multiple security issues in sanitization, serialization, and programmatic DOM handling. Most of these issues affected one of these advanced paths rather than ordinary parsed HTML with the default safe settings: - programmatic DOM input to sanitize or sanitizedom -...

GHSA-R758-8HXW-4845 justhtml: Mutation XSS with custom foreign-namespace sanitization policies

Summary A parser-differential / mutation XSS issue was found in justhtml when using a custom sanitization policy that preserves foreign namespaces such as SVG or MathML. Under these custom settings, specially crafted input could sanitize into HTML that looked safe at first, but became unsafe when...

Cross-site Scripting (XSS)

Overview justhtml is an A pure Python HTML5 parser that just works. Affected versions of this package are vulnerable to Cross-site Scripting XSS via the custom SanitizationPolicy if configured with dropforeignnamespaces=False or allowlisted foreign elements such as MathML or SVG or raw-text...

justhtml: Mutation XSS with custom foreign-namespace sanitization policies

Summary A parser-differential / mutation XSS issue was found in justhtml when using a custom sanitization policy that preserves foreign namespaces such as SVG or MathML. Under these custom settings, specially crafted input could sanitize into HTML that looked safe at first, but became unsafe when...