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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

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

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-wjv4-x9w8-wm3h?

O3 pinpoints whether GHSA-wjv4-x9w8-wm3h is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

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 34th 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 July 8, 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

GHSA-wjv4-x9w8-wm3h

GHSA-wjv4-x9w8-wm3h is a Use After Free vulnerability in nokogiri. O3 Security confirms whether GHSA-wjv4-x9w8-wm3h is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Nokogiri: Possible Use-After-Free when setting `Document#root=` to an invalid node type

Also known asCVE-2026-57436

Published

Jun 19, 2026

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 7, 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 CVEs34th percentile — riskier than 34% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

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

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nokogiri. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-wjv4-x9w8-wm3h is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-wjv4-x9w8-wm3h. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

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

Is GHSA-wjv4-x9w8-wm3h in your dependencies?

O3 detects GHSA-wjv4-x9w8-wm3h across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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