CVE-2021-4245 is a critical-severity (CVSS 9.8) CWE-74 vulnerability in rfc6902. 1 public exploit reference exists, so weaponization risk is real. A fix is available for rfc6902 — see the affected versions and patch details below.
npm package rfc6902 vulnerable to Prototype Pollution
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
CVE-2021-4245 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 377,333 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
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.
rfc6902npmDescription
A vulnerability classified as problematic has been found in chbrown rfc6902. This affects an unknown part of the file pointer.ts. The manipulation leads to improperly controlled modification of object prototype attributes ('prototype pollution'). The exploit has been disclosed to the public and may be used. The name of the patch is c006ce9faa43d31edb34924f1df7b79c137096cf. It is recommended to apply a patch to fix this issue. The associated identifier of this vulnerability is VDB-215883.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | rfc6902 | all versions | 5.0.0npm install rfc6902@5.0.0 |
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 rfc6902, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rfc6902 to 5.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-4245 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 CVE-2021-4245 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-4245. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-4245 in your dependencies?
O3 Security finds CVE-2021-4245 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.