# CVE-2026-57434: Nokogiri NULL pointer dereference in XML Node wrapper classes

Source: https://junglewise.ai/threats/cve-2026-57434-nokogiri-null-pointer-dereference-in-xml-node-wrapper-classes  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-25. Updated: 2026-06-25  
License: CC BY 4.0 with a link back

CVE-2026-57434 · Severity: medium · CVSS 4 · Published 2026-06-25

Nokogiri is a widely used Ruby library for processing XML and HTML data. A technical flaw in how the library handles uninitialized objects can lead to a program crash (denial of service). This issue is considered low risk because it requires a specific programming error in the application code rather than being triggered by malicious user input.

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

## Quick answers

**Is CVE-2026-57434 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-57434 being exploited in the wild.

**How severe is CVE-2026-57434?** Medium severity, with a CVSS score of 4, published 25 June 2026.

**Which products and versions are affected?** nokogiri (RubyGems) ECOSYSTEM:introduced=0,fixed=1.19.4.

**Is there a fix for CVE-2026-57434?** Yes. nokogiri (RubyGems): upgrade to 1.19.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-57434 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-57434?** 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 1.19.4 or later

  ```sh
  bundle update nokogiri
  ```


## Technical details

A NULL pointer dereference exists in Nokogiri's native wrapper classes inheriting from Nokogiri::XML::Node. The vulnerability is triggered when application code calls .allocate directly on a native-backed class and subsequently invokes methods on the resulting uninitialized object before proper initialization. This results in a crash of the Ruby process. The issue is limited to CRuby implementations; JRuby is not affected. A fix is available in version 1.19.4, which adds checks for missing native data pointers and raises a RuntimeError instead of crashing.

## Affected products

- sparklemotion Nokogiri < 1.19.4

## Identifiers

- CVE-2026-57434
- GHSA-9cv2-cfxc-v4v2

## Timeline

- 2026-06-18: advisory: GitHub Security Advisory published by maintainers
- 2026-06-25: disclosed: CVE published to NVD

## References

- [https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-9cv2-cfxc-v4v2](https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-9cv2-cfxc-v4v2)

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