CVE-2019-20149 is a high-severity (CVSS 7.5) CWE-668 vulnerability in kind-of. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2019-20149 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Validation Bypass in kind-of
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
kind-ofnpmDescription
ctorName in index.js in kind-of v6.0.2 allows external user input to overwrite certain internal attributes via a conflicting name, as demonstrated by 'constructor': {'name':'Symbol'}. Hence, a crafted payload can overwrite this builtin attribute to manipulate the type detection result.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | kind-of | ≥ 6.0.0&&< 6.0.3 | 6.0.3 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kind-of. 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 kind-of to 6.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-20149 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 CVE-2019-20149 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 CVE-2019-20149. 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.
While some components do package a vulnerable version of `kind-of`, access to them requires OpenShift OAuth credentials and hence have been marked with a Low impact. This applies to the following products: - OpenShift ServiceMesh (OSSM) - Red Hat Advanced Cluster Management for Kubernetes (RHACM) - OpenShift…
Frequently Asked Questions
Is CVE-2019-20149 in your dependencies?
O3 detects CVE-2019-20149 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.