NokogiriApplication
CVE-2026-57436
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 · uneditedNokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::Document#root= validated only that the new root was a Nokogiri::XML::Node, allowing a DTD node to be set as the document root. The result is a heap use-after-free during garbage collection or finalization, leading to an invalid memory read or potentially a segfault. 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 confidenceIn Nokogiri versions prior to 1.19.4, the Document#root= setter only validated that the assigned node was a Nokogiri::XML::Node but failed to exclude DTD (Document Type Definition) nodes. When a DTD node is set as the document root, garbage collection or finalization triggers a heap use-after-free vulnerability, causing invalid memory reads or potential segfaults.
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
< 1.19.4CVSS 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
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 checksWork through these to decide whether this CVE applies to you.
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Check installed Nokogiri versionRun `gem list nokogiri` or in Ruby: `require 'nokogiri'; puts Nokogiri::VERSION`Affected if Version is lower than 1.19.4 (e.g., 1.19.3, 1.18.x, etc.)
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Locate usage of Document#root= setterSearch codebase for calls to `.root =` on Nokogiri::XML::Document objects, or search for `doc.root =` patterns in Ruby filesAffected if Code assigns a value to document.root using the setter method
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Identify if DTD nodes are being assigned as rootSearch for patterns where a DTD node (e.g., result of `doc.children.find { |n| n.class == Nokogiri::XML::DTD }` or similar DTD retrieval) is passed to the root= setterAffected if Any code path passes a DTD node object to the root= setter, triggering the vulnerable code path
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Verify Ruby garbage collection behaviorThe vulnerability triggers during garbage collection or finalization of the DTD node, typically observable during document lifecycle operations or scope exitsAffected if Application processes XML documents where DTD nodes could be set as root, and experiences segfaults or memory errors during GC cycles
Environment is affected if Nokogiri version is below 1.19.4 AND code uses Document#root= setter with potential DTD node assignment, leading to use-after-free during garbage collection.
Generated from the published advisory. Verify against your own configuration.
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 · scoped1.19.4
Upgrade Nokogiri to version 1.19.4 or later to receive the patch that adds proper node type validation to reject DTD nodes as document roots. Test thoroughly after upgrading to ensure compatibility with existing XML processing workflows.
Nokogiri 1.19.4
- Run `gem install nokogiri -v 1.19.4` to install the fixed version
- If using Bundler, update your Gemfile or Gemfile.lock to specify `gem 'nokogiri', '~> 1.19.4'` and run `bundle install`
- Verify the installed version by running `gem list nokogiri` or `Nokogiri::VERSION` in Ruby
- Test your application to confirm the upgrade does not introduce regressions
- If using a Gemfile.lock, consider running `bundle update nokogiri` to ensure the lock file reflects the new version
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Nokogiri
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-57436 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-57436 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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