HtmlSanitizer

Releases

1. ▸▾10.0.1075-beta1 Oct 2026pre-release

   Nothing published for this version

2. ▸▾10.0.1037-beta27 Aug 2026pre-releaseBreaking

   First beta of a major version. Please test against your usage before GA — see Breaking changes below, especially if you have a custom IHtmlSanitizer i…

   First beta of a major version. Please test against your usage before GA — see Breaking changes below, especially if you have a custom IHtmlSanitizer implementation or construct HtmlSanitizerOptions yourself.

   Breaking changes

   • IHtmlSanitizer gained new members. Anything implementing the interface directly (not just consuming HtmlSanitizer) needs updating: StyleFormatter, EncodeComment, EncodeLiteralTextElementContent, UriListAttributes, AllowCssCustomProperties, the FilterCssRule event, both SanitizeFragment overloads, and SanitizeDocument(Stream, ...).
   • HtmlSanitizerOptions collections are now pre-populated by default. new HtmlSanitizerOptions() now seeds every collection from HtmlSanitizerDefaults — the same defaults new HtmlSanitizer() uses — instead of starting empty (#570). If you build HtmlSanitizerOptions yourself, audit it: code that relied on the old emptiness to build a minimal allowlist (e.g. setting only AllowedTags and expecting everything else to stay locked down) now gets the full default attribute/scheme/URI-attribute set for anything it doesn't explicitly reassign. Use the new HtmlSanitizerOptions.Empty() for the old blank-slate behavior.
   • HtmlSanitizerOptions.AllowedCssClasses renamed to AllowedClasses, matching HtmlSanitizer.AllowedClasses / IHtmlSanitizer.AllowedClasses. It's also now case-insensitive by default like every other collection on the class (it wasn't before — a latent bug).
   • SanitizeDom(string) no longer preserves attributes on the synthetic <html>/<head>/<body> wrapper elements it creates. Fixes an attribute-injection bypass (e.g. <body onload=alert(1)>) for callers that serialize more of the returned document than dom.Body.ChildNodes.
   • AssemblyVersion bumped to 10.0.0.0. Update any binding redirects pinned to 9.0.0.0.

   New

   • SanitizeFragment(html, context, ...) — sanitize a fragment as if inserted into a given element/tag context (e.g. tr, ul) instead of always parsing under <body>, so context-dependent markup like a lone <th> survives.
   • SanitizeDocument(Stream, ...) overload.
   • UriListAttributes — screens attributes holding a list of URLs (srcset, ping) entry-by-entry, rather than as one URL.
   • AllowCssCustomProperties — opt in to allowing CSS custom properties (--*).
   • StyleFormatter, EncodeComment, EncodeLiteralTextElementContent — now configurable on the sanitizer/interface.
   • FilterCssRule event, raised per CSS rule during sanitization.
   • HtmlSanitizerOptions.Empty() for building an allowlist from scratch.

   Security / stricter sanitization

   Output for some previously-passing input is now more restrictive:

   • cite and longdesc are now screened as URL attributes.
   • @font-face and @import at-rule declarations are now sanitized.
   • srcdoc content is now recursively sanitized, and URI-list attributes (srcset, ping) are screened per-entry.
   • <style type=""> content is now sanitized (previously an empty type could skip CSS filtering).
   • Fixed CSS var-in-shorthand handling and a resolved-URI check.
   • Fixed multiple enumeration of URLs (#625) and #629.
   • Foreign-namespace contexts (SVG/MathML) are now rejected by SanitizeFragment rather than silently mis-parsed under HTML rules.

   Dependencies

   • AngleSharp 1.7.1 → 1.7.2, AngleSharp.Css 1.0.1 → 1.0.2.