GHSA-v2fc-qm4h-8hqv — nokogiri
MEDIUMGHSA-v2fc-qm4h-8hqv is a medium-severity (CVSS 5.3) CWE-401 vulnerability in nokogiri. A fix is available for nokogiri — see the affected versions and patch details below.
Nokogiri XSLT transform has a memory leak
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 GHSA-v2fc-qm4h-8hqv.
EPSS Exploitation Probability
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.
How urgent is this, really
GHSA-v2fc-qm4h-8hqv plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
nokogiriReal-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 Nokogiri::XSLT::Stylesheet#transform leaks a small heap allocation when passed a Ruby string parameter containing a null byte.
For applications that pass attacker-controlled input through XSLT.transform parameters, this may be a vector for a denial of service attack against long-running processes.
Mitigation
Upgrade to Nokogiri >= 1.19.3.
Users may also be able to mitigate this issue without upgrading by validating untrusted transform parameters before passing them to Nokogiri::XSLT::Stylesheet#transform.
Severity
The Nokogiri maintainers have evaluated this as Moderate Severity, CVSS 5.3.
Each leaked allocation is approximately 24–32 bytes, so meaningful memory growth requires sustained attacker-controlled traffic at high call rates. The bug does not cause memory corruption, information disclosure, or any change in the behavior of the transform itself, and the string-handling exception is raised as expected.
Applications that do not pass raw attacker-controlled bytes to XSLT parameters are unlikely to be affected in practice.
Resources
Credit
This vulnerability was responsibly reported by @Captainjack-kor.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | nokogiri | all versions | 1.19.3bundle update nokogiri --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
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 1.19.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-v2fc-qm4h-8hqv 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-v2fc-qm4h-8hqv can be triaged on real exposure rather than presence alone.
Tailored to GHSA-v2fc-qm4h-8hqv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-v2fc-qm4h-8hqv in your dependencies?
O3 Security finds GHSA-v2fc-qm4h-8hqv across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.