Answer in brief
CVE-2026-126063 records a Low severity (CVSS 2.3) vulnerability in Nokogiri: Mutation XSS through `noscript` content in Nokogiri's HTML5 serializer. The current sources do not mark it as known exploited. The current feed maps sparklemotion/nokogiri (generic), nokogiri (rubygems), nokogiri (rubygems). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 2.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps sparklemotion/nokogiri (generic), nokogiri (rubygems), nokogiri (rubygems). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| sparklemotion/nokogirigeneric | >=1.12.0 <1.19.5 | 1.19.5 |
| nokogirirubygems | >=1.12.0,<1.19.5 | 1.19.5 |
| nokogirirubygems | >=1.12.0 <1.19.5 | 1.19.5 |
Published upstream
Nov 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 10, 2026
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.
Quoted source text, attributed separately from HOL analysis.