# CVE-2026-126062: JRuby: NONET is bypassed for external DTDs and entities when the systemId uses a short-form IPv4 host

Source: https://junglewise.ai/threats/cve-2026-126062-nokogiri-is-an-open-source-xml-and-html-library-for-the-ruby  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-126062 · Severity: low · CVSS 3.7 · Published 2026-11-10

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.5, on JRuby, applications that parse untrusted XML with DTDLOAD, DTDVALID, or NOENT can have the NONET restriction bypassed when an external DTD or entity uses a short-form IPv4 host or uses absolute paths resolved against a network URL. The resolver can treat these identifiers as local and send a network request, potentially enabling server-side request forgery. CRuby and default parse options are not affected. This issue is fixed in version 1.19.5.

Technologies: [nokogiri (RubyGems)](https://junglewise.ai/threats/technologies/nokogiri). Vendors: [RubyGems](https://junglewise.ai/threats/vendors/rubygems).

## Quick answers

**Is CVE-2026-126062 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126062 being exploited in the wild.

**How severe is CVE-2026-126062?** Low severity, with a CVSS score of 3.7, published 10 November 2026.

**Which products and versions are affected?** nokogiri (RubyGems) < 1.19.5, ECOSYSTEM:introduced=0,fixed=1.19.5.

**Is there a fix for CVE-2026-126062?** Yes. nokogiri (RubyGems): upgrade to 1.19.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-126062?** Check whether you run nokogiri (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- nokogiri (RubyGems): upgrade to 1.19.5 or later

  ```sh
  bundle update nokogiri
  ```


## Affected products

- nokogiri (RubyGems) < 1.19.5, ECOSYSTEM:introduced=0,fixed=1.19.5

## Identifiers

- CVE-2026-126062
- GHSA-v995-44v6-5fqm

## Related threats

- [Nokogiri use-after-free in attribute replacement](https://junglewise.ai/threats/cve-2026-126064-nokogiri-is-an-open-source-xml-and-html-library-for-the-ruby)
- [Nokogiri HTML5 serializer mutation XSS via noscript and attributes](https://junglewise.ai/threats/cve-2026-126063-nokogiri-is-an-open-source-xml-and-html-library-for-the-ruby)
- [Nokogiri unchecked return value in canonicalize method](https://junglewise.ai/threats/nokogiri-unchecked-return-value-in-canonicalize-method-3863de91)
- [Nokogiri XSLT transform memory leak](https://junglewise.ai/threats/nokogiri-xslt-transform-memory-leak-0441ddf7)
- [Nokogiri CSS selector tokenizer ReDoS](https://junglewise.ai/threats/nokogiri-css-selector-tokenizer-redos-d52ae203)