# CVE-2026-57437: Nokogiri use-after-free in XML::XPathContext

Source: https://junglewise.ai/threats/cve-2026-57437-nokogiri-use-after-free-in-xml-xpathcontext  
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-2026-57437 · Severity: medium · CVSS 4 · Published 2026-06-25

Nokogiri is a widely used Ruby library for processing XML and HTML documents. A technical flaw in how the library manages memory could cause an application to crash (segmentation fault) if it uses a specific, advanced programming pattern. This issue does not affect standard document searching and cannot be triggered by malicious user input alone; it requires a specific sequence of events in the application's own code.

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

## Quick answers

**Is CVE-2026-57437 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-57437 being exploited in the wild.

**How severe is CVE-2026-57437?** 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-2026-57437?** 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-2026-57437 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-57437?** 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 Use-After-Free (CWE-416) vulnerability exists in the CRuby implementation of Nokogiri. The `Nokogiri::XML::XPathContext` class failed to maintain a reference to its parent XML document, allowing the Ruby garbage collector to reclaim the document's memory while the context was still in use. If an application manually constructs an `XPathContext` and the source document is collected, subsequent XPath evaluations will read invalid memory, leading to a segmentation fault. This is not triggerable via malicious XML input and does not affect the high-level `Document#xpath` or `#css` methods. The issue is resolved in version 1.19.4 by ensuring the context keeps the source document alive.

## Affected products

- sparklemotion Nokogiri < 1.19.4

## Identifiers

- CVE-2026-57437
- GHSA-p67v-3w7g-wjg7

## Timeline

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

## References

- [https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-p67v-3w7g-wjg7](https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-p67v-3w7g-wjg7)

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