CVE-2026-126063

UNKNOWN 0.0

Nokogiri: Mutation XSS through `noscript` content in Nokogiri's HTML5 serializer

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

Nokogiri is an open source XML and HTML library for the Ruby programming language. From 1.12.0 until 1.19.5, the C extension on CRuby and TruffleRuby has a Nokogiri::HTML5 serializer that does not escape text inside noscript elements or angle brackets inside attribute values. When an application sanitizes untrusted HTML with the default parsing options, allows noscript, and sends serialized output to a scripting-enabled browser, the browser can parse markup that Nokogiri did not produce, enabling mutation cross-site scripting. Using parse_noscript_content_as_text: true is the recommended workaround, not the vulnerable default. JRuby is not affected because it does not implement Nokogiri::HTML5. This issue is fixed in version 1.19.5.

CWE	CWE-79 CWE-116
Vendor	sparklemotion
Product	nokogiri
Published	Nov 10, 2026

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Affected Versions

sparklemotion / nokogiri

>= 1.12.0, < 1.19.5

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-4p39-36wj-23h4 github.com: https://github.com/sparklemotion/nokogiri/pull/3752 github.com: https://github.com/sparklemotion/nokogiri/commit/3e84df6ff7ab4d78f446e3a415430bd69a055d32 github.com: https://github.com/sparklemotion/nokogiri/commit/c6c0bffbdcd194694995acafeeed27326b0805f8 github.com: https://github.com/sparklemotion/nokogiri/releases/tag/v1.19.5