CVE-2026-126203

NameCVE-2026-126203
DescriptionLoofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.21.0 until 2.25.3, Loofah's HTML5 APIs Loofah.html5_fragment, Loofah.html5_document, and the scrub_html5_* methods can emit sanitized output that a browser reparses as different markup when used with Nokogiri before 1.19.5, because those Nokogiri versions do not escape angle brackets in attribute values. MathML can place markup inside an allowed attribute so the reparsed output becomes live HTML. The :strip scrubber is affected in every browser, while :prune and :escape are affected in WebKit browsers. Loofah's HTML4 APIs, Loofah::Helpers.sanitize, :whitewash, rails-html-sanitizer's default configuration, and JRuby are not affected. This issue is fixed in version 2.25.3.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
ruby-nokogiri (PTS)bookworm1.13.10+dfsg-2vulnerable
trixie1.18.2+dfsg-1vulnerable
forky1.19.4+dfsg-1vulnerable
sid1.19.7+dfsg-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
ruby-nokogirisource(unstable)1.19.7+dfsg-1

Notes

https://github.com/flavorjones/loofah/security/advisories/GHSA-h6v6-rg66-fqj4
https://github.com/flavorjones/loofah/pull/324
https://github.com/sparklemotion/nokogiri/commit/635abc8d65c75d594ddf8957fbfbfd822c2c0dbd (v1.19.5)
Loofah only bumped the required version, the underlying fix is in nokogiri

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