---
id: GHSA-phwj-rprq-35pp
title: >-
  Nokogiri: Possible Use-After-Free when setting an attribute value via
  `Nokogiri::XML::Attr#value=` or `#content=`
summary: >-
  Nokogiri: Possible Use-After-Free when setting an attribute value via
  `Nokogiri::XML::Attr#value=` or `#content=`
severity: low
cwe:
  - CWE-416
  - CWE-825
vendor: nokogiri
product: nokogiri
affected:
  - nokogiri < 1.19.4
patched:
  - nokogiri 1.19.4
published: '2026-06-19'
updated: '2026-06-19'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-phwj-rprq-35pp'
references:
  - url: >-
      https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-phwj-rprq-35pp
  - url: 'https://github.com/advisories/GHSA-phwj-rprq-35pp'
tags:
  - ghsa
  - rubygems
ingestedAt: '2026-06-22T15:52:21.087Z'
ecosystem: rubygems
---

## Overview

### Summary

Nokogiri’s CRuby native extension could leave a Ruby wrapper pointing to freed memory when replacing the value of an XML attribute. If Ruby code had already accessed an attribute child node, `Nokogiri::XML::Attr#value=` could free the underlying native child node while the wrapper remained reachable through the document node cache. A later use of the freed child node or a Ruby GC mark could dereference an invalid pointer, causing an invalid read and a possible segfault.

Nokogiri 1.19.4 preserves any already-wrapped attribute child nodes before replacing the attribute value.

JRuby is not affected.

### Severity

The Nokogiri maintainers have evaluated this as low severity. Reaching it requires an unusual API-usage pattern that does not arise during normal use. The application must directly access an attribute's child node and then replace that same attribute's value via `Attr#value=` or `#content=`. Nokogiri 1.19.4 makes this pattern safe with no change to the public API. Already-wrapped attribute child nodes are preserved before the value is replaced.

### Mitigation

Upgrade to Nokogiri 1.19.4 or later.

As a workaround, avoid accessing attribute child nodes directly via `Attr#child` or similar before mutating the same attribute’s value.

### Credit

This issue was responsibly reported by Zheng Yu from depthfirst.com.

## Affected packages

- `nokogiri < 1.19.4`

## Remediation

Upgrade to a patched release:

- `nokogiri 1.19.4`