NokogiriApplication
CVE-2026-57435
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’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. 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 confidenceNokogiri versions prior to 1.19.4 contain a use-after-free vulnerability in the CRuby native extension. When replacing an XML attribute value via Nokogiri::XML::Attr#value= after previously accessing the attribute's child node, the underlying native child node gets freed while its Ruby wrapper remains cached in the document. Subsequent access or Ruby GC can dereference an invalid pointer, causing an invalid memory read and potential segfault.
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
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 checksWork through these to decide whether this CVE applies to you.
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Check installed Nokogiri versionRun 'gem list nokogiri' or add this Ruby code to your application: puts Nokogiri::VERSIONAffected if Version is less than 1.19.4 (e.g., 1.19.3, 1.18.x, etc.)
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Confirm CRuby (MRI) runtime is in useCheck that your Ruby interpreter is CRuby/MRI (not JRuby or TruffleRuby). Run 'ruby --version' - if it says 'jruby' or 'truffleruby', this specific vulnerability does not apply.Affected if Running on CRuby/MRI and Nokogiri version is less than 1.19.4
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Identify code using Nokogiri::XML::Attr#value=Search your codebase for calls to the value= method on Nokogiri::XML::Attr objects, for example: attr_node.value = 'new_value'Affected if Your code sets attribute values via attr.value= after previously calling methods that access the attribute's child nodes (such as children.first, children.each, or iterating over child nodes)
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Review attribute access patternsExamine whether attribute child nodes are accessed before the value= replacement. Look for patterns like: node['attr_name'].children.first or iterating over node['attr_name'].children before calling value= on that attribute.Affected if Code accesses an attribute's children or child nodes before replacing that attribute's value using value=
You are affected if running Nokogiri version below 1.19.4 on CRuby/MRI and your code specifically accesses an attribute's child nodes before replacing that attribute's value via the value= method.
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 remediate this use-after-free vulnerability.
Nokogiri 1.19.4
- Check current Nokogiri version with: gem list nokogiri
- Update Nokogiri to version 1.19.4 or later using: gem install nokogiri -v '>= 1.19.4'
- For projects using Bundler, run: bundle update nokogiri
- Verify the fix by checking: Nokogiri::VERSION => '1.19.4' or higher
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Nokogiri
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 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 $2,464.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-57435 — 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-2026-57435 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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