CVE-2026-57236: Nokogiri: Possible Use-After-Free when `Nokogiri::XML::Document#encoding=` raises an exception

Published Jun 25, 2026
·
Updated

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, calling Document#encoding= with an invalid encoding (e.g., a non-string, or a string containing a null byte) raises an exception, but only after freeing the document's current encoding string without replacing it. The document is left referencing freed memory, so the next call to Document#encoding reads invalid memory, which can cause a segfault or leak freed bytes into a Ruby String. Affects the CRuby (libxml2) implementation only; JRuby is not affected. This vulnerability is fixed in 1.19.4.

Other sources

Nokogiri: Possible Use-After-Free when Nokogiri::XML::Document#encoding= raises an exception

— Microsoft

Affected Software

4 affected componentsFixes available
Nokogiri<1.19.4
Nokogiri Nokogiri Ruby<1.19.4
Microsoft azl3 rubygem-nokogiri 1.15.4-1<1.19.4-1
1.19.4-1
IBM Aspera Faspex 5<=5.0.0 - 5.0.15.4

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.19.4-1
  2. Upgrade

    Upgrade Nokogiri to a version that resolves this vulnerability.

    Fixed in 1.19.4

Event History

Jun 25, 2026
CVE Published
via MITRE·02:29 PM
Data Sourced
via MITRE·02:29 PM
DescriptionWeakness
Data Sourced
via NVD·03:16 PM
DescriptionSeverityWeaknessAffected Software
Jun 27, 2026
Data Sourced
via Microsoft·08:16 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:16 AM
DescriptionSeverity
Jul 20, 2026
Data Sourced
via IBM·12:00 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

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Frequently Asked Questions

1

What is the severity of CVE-2026-57236?

The severity of CVE-2026-57236 is rated as risk 37.

2

How do I fix CVE-2026-57236?

To fix CVE-2026-57236, update Nokogiri to version 1.19.4 or later.

3

What kind of vulnerability is CVE-2026-57236?

CVE-2026-57236 is categorized as a Use After Free vulnerability.

4

When was CVE-2026-57236 published?

CVE-2026-57236 was published on June 25, 2026.

5

What is affected by CVE-2026-57236?

CVE-2026-57236 affects the Nokogiri library for Ruby when handling invalid encodings.

Company

Resources

Contact

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CVE-2026-57236 - Nokogiri: Possible Use-After-Free when `Nokogiri::XML::Document#encoding=` raises an exception - SecAlerts