GHSA-vr8q-g5c7-m54m is a medium-severity (CVSS 4.3) XML External Entity (XXE) vulnerability in nokogiri. O3 Security confirms whether GHSA-vr8q-g5c7-m54m is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Nokogiri::XML::Schema trusts input by default, exposing risk of XXE vulnerability
Real-World Exposure
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Description
Severity
Nokogiri maintainers have evaluated this as Low Severity (CVSS3 2.6).
Description
In Nokogiri versions <= 1.11.0.rc3, XML Schemas parsed by Nokogiri::XML::Schema are trusted by default, allowing external resources to be accessed over the network, potentially enabling XXE or SSRF attacks.
This behavior is counter to the security policy followed by Nokogiri maintainers, which is to treat all input as untrusted by default whenever possible.
Please note that this security fix was pushed into a new minor version, 1.11.x, rather than a patch release to the 1.10.x branch, because it is a breaking change for some schemas and the risk was assessed to be "Low Severity".
Affected Versions
Nokogiri <= 1.10.10 as well as prereleases 1.11.0.rc1, 1.11.0.rc2, and 1.11.0.rc3
Mitigation
There are no known workarounds for affected versions. Upgrade to Nokogiri 1.11.0.rc4 or later.
If, after upgrading to 1.11.0.rc4 or later, you wish to re-enable network access for resolution of external resources (i.e., return to the previous behavior):
- Ensure the input is trusted. Do not enable this option for untrusted input.
- When invoking the
Nokogiri::XML::Schemaconstructor, pass as the second parameter an instance ofNokogiri::XML::ParseOptionswith theNONETflag turned off.
So if your previous code was:
# in v1.11.0.rc3 and earlier, this call allows resources to be accessed over the network
# but in v1.11.0.rc4 and later, this call will disallow network access for external resources
schema = Nokogiri::XML::Schema.new(schema)
# in v1.11.0.rc4 and later, the following is equivalent to the code above
# (the second parameter is optional, and this demonstrates its default value)
schema = Nokogiri::XML::Schema.new(schema, Nokogiri::XML::ParseOptions::DEFAULT_SCHEMA)
Then you can add the second parameter to indicate that the input is trusted by changing it to:
# in v1.11.0.rc3 and earlier, this would raise an ArgumentError
# but in v1.11.0.rc4 and later, this allows resources to be accessed over the network
schema = Nokogiri::XML::Schema.new(trusted_schema, Nokogiri::XML::ParseOptions.new.nononet)
References
- This issue's public advisory
- Original Hackerone report (private)
- OWASP description of XXE attack
- OWASP description of SSRF attack
Credit
This vulnerability was independently reported by @eric-therond and @gucki.
The Nokogiri maintainers would like to thank HackerOne for providing a secure, responsible mechanism for reporting, and for providing their fantastic service to us.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | nokogiri | all versions | 1.11.0 |
Detection & mitigation playbook
Open-source dependencyDetect
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 1.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vr8q-g5c7-m54m 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-vr8q-g5c7-m54m 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-vr8q-g5c7-m54m. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
Frequently Asked Questions
Is GHSA-vr8q-g5c7-m54m in your dependencies?
O3 detects GHSA-vr8q-g5c7-m54m across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.