# CVE-2026-57235: Nokogiri out-of-bounds read in NodeSet indexing

Source: https://junglewise.ai/threats/cve-2026-57235-nokogiri-out-of-bounds-read-in-nodeset-indexing  
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-2026-57235 · Severity: medium · CVSS 4 · Published 2026-06-25

Nokogiri is a widely used Ruby library for processing XML and HTML data. A vulnerability in how the library handles specific data requests could allow an attacker to crash an application or potentially access unintended memory. This could lead to service outages or the exposure of sensitive information if the application processes untrusted user input.

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

## Quick answers

**Is CVE-2026-57235 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-57235 being exploited in the wild.

**How severe is CVE-2026-57235?** 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-2026-57235?** 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-2026-57235 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-57235?** 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

An out-of-bounds read vulnerability exists in Nokogiri's NodeSet indexing logic due to integer truncation. The library's bounds-checking mechanism used a 32-bit truncated copy of the requested index, allowing large negative indices to bypass validation. When the full-width index is subsequently used for memory access, it results in an out-of-bounds read. On CRuby, this typically causes a process crash (DoS) or potential memory disclosure, while on JRuby it returns incorrect nodes. The vulnerability is reachable if an application passes attacker-controlled integers to the NodeSet#[] or #slice methods. This issue is fixed in version 1.19.4.

## Affected products

- sparklemotion Nokogiri < 1.19.4

## Identifiers

- CVE-2026-57235
- GHSA-5prr-v3j2-97mh

## 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-5prr-v3j2-97mh](https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-5prr-v3j2-97mh)

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- [JRuby: NONET is bypassed for external DTDs and entities when the systemId uses a short-form IPv4 host](https://junglewise.ai/threats/cve-2026-126062-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)