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NokogiriApplication

CVE-2026-57236

HIGH · 8.2 CVSS v3.1 Published 2026-06-25
Fix available
A fix is available. Upgrade to 1.19.4 or later.
See remediation →
91/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Nokogiri versions prior to 1.19.4 have a use-after-free vulnerability in the CRuby/libxml2 implementation. When Document#encoding= is called with an invalid encoding (non-string or null-byte string), the document's current encoding string is freed but not replaced before an exception is raised. Subsequent reads of Document#encoding reference freed memory, causing potential segfaults or information disclosure via leaked freed bytes into Ruby strings.

MitigationUpgrade Nokogiri to version 1.19.4 or later to remediate this use-after-free vulnerability in the CRuby implementation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
NokogiriApplication
Affected:< 1.19.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Nokogiri version
    Run `gem list nokogiri` or `ruby -e 'require "nokogiri"; puts Nokogiri::VERSION'`
    Affected if Version is below 1.19.4
  2. Confirm CRuby implementation is in use
    Run `ruby -e 'require "nokogiri"; puts Nokogiri::LIBXML_VERSION'` - if a version number prints, you are using the CRuby/libxml2 implementation rather than JRuby
    Affected if Using the CRuby (not JRuby) implementation of Nokogiri
  3. Search codebase for Document#encoding= usage
    Grep your source code for patterns such as `.encoding =` or `.encoding=` being called on Nokogiri::XML::Document or Nokogiri::HTML::Document objects
    Affected if Code assigns to the encoding= method with non-string values or strings containing null bytes
  4. Monitor for segfaults or corrupted string data
    Review application logs and crash dumps for segmentation faults occurring after encoding assignments, or inspect any Ruby string values that contain unexpected random or binary data
    Affected if Segfaults occur or string values become corrupted after setting document encoding

You are affected if running Nokogiri version below 1.19.4 with the CRuby implementation and your application calls Document#encoding= with invalid encoding values.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.19.4 or later
Fixed in 1.19.4
Interim mitigation

Upgrade Nokogiri to version 1.19.4 or later to remediate this use-after-free vulnerability in the CRuby implementation.

Recommended fix High confidence

1.19.4

  1. Update the Nokogiri gem to version 1.19.4 or later by running `gem install nokogiri -v '>= 1.19.4'` or updating your Gemfile with `gem 'nokogiri', '>= 1.19.4'`
  2. Run `bundle update nokogiri` to update the dependency in your project
  3. Verify the installed version with `nokogiri -v` or by checking `Gem::Specification.find_by_name('nokogiri').version` to confirm version 1.19.4 or later is installed
  4. Test your application to ensure the upgrade does not break existing functionality

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nokogiri Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-57236 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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