How severe is CVE-2026-79772?

No CVSS score has been assigned to CVE-2026-79772 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-79772?

CVE-2026-79772 affects the following packages: nokogiri (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2026-79772?

Update nokogiri to 1.19.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-79772 is resolved across your whole dependency graph.

How do I detect CVE-2026-79772 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 CVE-2026-79772 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.

Is CVE-2026-79772 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-79772 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 CVE-2026-79772?

CVE-2026-79772 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 26th 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 CVE-2026-79772?

CVE-2026-79772 is classified as CWE-252 (CWE-252). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-79772 published, and has it been updated?

CVE-2026-79772 was published on August 25, 2026 and was last updated on September 3, 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

CVE-2026-79772 — nokogiri

CVE-2026-79772 is a CWE-252 vulnerability in nokogiri. A fix is available for nokogiri — see the affected versions and patch details below.

Nokogiri before 1.19.1 Unchecked Return Value canonicalize

Also known asGHSA-wx95-c6cv-8532

Published

Aug 25, 2026

Updated

Sep 3, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 23, 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.
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 CVE-2026-79772.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs26th percentile — riskier than 26% 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's CRuby extension fails to check the return value from xmlC14NExecute in the method Nokogiri::XML::Document#canonicalize and Nokogiri::XML::Node#canonicalize. When canonicalization fails, an empty string is returned instead of raising an exception. This incorrect return value may allow downstream libraries to accept invalid or incomplete canonicalized XML, which has been demonstrated to enable signature validation bypass in SAML libraries.

JRuby is not affected, as the Java implementation correctly raises RuntimeError on canonicalization failure.

Mitigation

Upgrade to Nokogiri >= 1.19.1.

Severity

The maintainers have assessed this as Medium severity. Nokogiri itself is a parsing library without a clear security boundary related to canonicalization, so the direct impact is that a method returns incorrect data on invalid input. However, this behavior was exploited in practice to bypass SAML signature validation in downstream libraries (see References).

Credit

This vulnerability was responsibly reported by HackerOne researcher d4d.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`nokogiri`	≥ 1.5.1&&< 1.19.1	1.19.1`bundle update nokogiri --conservative`

Affected Products

1 product · 1 configurations

Application

nokogirinokogiri

≥ 1.5.1 && < 1.19.1

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 1.19.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-79772 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.

Frequently Asked Questions

## Summary Nokogiri's CRuby extension fails to check the return value from `xmlC14NExecute` in the method `Nokogiri::XML::Document#canonicalize` and `Nokogiri::XML::Node#canonicalize`. When canonicalization fails, an empty string is returned instead of raising an exception. This incorrect return value may allow downstream libraries to accept invalid or incomplete canonicalized XML, which has been demonstrated to enable signature validation bypass in SAML libraries. JRuby is not affected, as the Java implementation correctly raises `RuntimeError` on canonicalization failure. ## Mitigation U

O3 Security · Impact-Aware SCA

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