How severe is GHSA-wjv4-x9w8-wm3h?

No CVSS score has been assigned to GHSA-wjv4-x9w8-wm3h yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-wjv4-x9w8-wm3h?

GHSA-wjv4-x9w8-wm3h affects the following packages: nokogiri (RubyGems). Ecosystems affected: RubyGems.

How do I fix GHSA-wjv4-x9w8-wm3h?

Update nokogiri to 1.19.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wjv4-x9w8-wm3h is resolved across your whole dependency graph.

How do I detect GHSA-wjv4-x9w8-wm3h in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nokogiri, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-wjv4-x9w8-wm3h if there is no patch (or I can't update yet)?

Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Is GHSA-wjv4-x9w8-wm3h actively exploited in the wild?

No public exploit code has been indexed for GHSA-wjv4-x9w8-wm3h yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-wjv4-x9w8-wm3h?

GHSA-wjv4-x9w8-wm3h has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 33th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-wjv4-x9w8-wm3h?

GHSA-wjv4-x9w8-wm3h is classified as Use After Free (CWE-416). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-wjv4-x9w8-wm3h published, and has it been updated?

GHSA-wjv4-x9w8-wm3h was published on June 19, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

Not in CISA KEV

Nokogiri: Possible Use-After-Free when setting `Document#root=` to an invalid node typeGHSA-wjv4-x9w8-wm3h

GHSA-wjv4-x9w8-wm3h is a Use After Free vulnerability in nokogiri. A fix is available for nokogiri — see the affected versions and patch details below.

Also known asCVE-2026-57436

Published

Jun 19, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-wjv4-x9w8-wm3h.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs33th percentile — riskier than 33% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

💎nokogiri

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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.

Nokogiri 1.19.4 restricts Document#root= to element nodes, raising TypeError for any other node type.

This memory-safety issue affects only the CRuby implementation (libxml2). The JRuby implementation was not affected; the same input validation was added there for behavioral parity.

Severity

The Nokogiri maintainers have evaluated this as low severity. This is only triggered by a programming error. It requires application code to assign a non-element node such as a DTD as the document root via Document#root=. Nokogiri 1.19.4 now raises TypeError instead of allowing a use-after-free. It cannot be triggered by untrusted input or through normal use of the public API.

Mitigation

Upgrade to Nokogiri 1.19.4 or later.

As a workaround, applications that cannot upgrade should avoid assigning a DTD (or any non-element node) via Document#root=.

Credit

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`nokogiri`	all versions	1.19.4`bundle update nokogiri --conservative`

Affected Products

1 product · 1 configurations

Application

nokogirinokogiri

< 1.19.4

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nokogiri, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nokogiri to 1.19.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wjv4-x9w8-wm3h is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatLow

This is a flaw in Nokogiri, a Ruby library for XML and HTML processing, that can result in a denial of service. The vulnerability stems from insufficient validation when setting the document root, allowing a malicious XML document to trigger a heap use-after-free. This could lead to application crashes and impact the…

Workaround published by Red Hat

To mitigate this issue, applications that use Nokogiri to process untrusted XML or HTML documents should implement robust input validation and operate within a sandboxed environment. Restricting the application's ability to process arbitrary external content can reduce the risk of triggering the heap use-after-free vulnerability and prevent a denial of service.

Source: Red Hat security advisory for GHSA-wjv4-x9w8-wm3h (CC BY 4.0)

Frequently Asked Questions

### Summary `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. Nokogiri 1.19.4 restricts `Document#root=` to element nodes, raising `TypeError` for any other node type. This memory-safety issue affects only the CRuby implementation (libxml2). The JRuby implementation was not affected; the same input validation was added there for behavioral parity. ### Severi

O3 Security · Impact-Aware SCA

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