CVE-2020-7699 is a critical-severity (CVSS 9.8) CWE-1321 vulnerability in express-fileupload. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for express-fileupload — see the affected versions and patch details below.
Prototype Pollution in express-fileupload
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
express-fileuploadnpmDescription
This affects the package express-fileupload before 1.1.8. If the parseNested option is enabled, sending a corrupt HTTP request can lead to denial of service or arbitrary code execution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | express-fileupload | all versions | 1.1.9npm install express-fileupload@1.1.9 |
Affected Products
express-fileuploadexpress-fileupload_projectmax datanetappResearch 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 express-fileupload, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update express-fileupload to 1.1.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-7699 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2020-7699 in your dependencies?
Find it across npm, including transitive dependencies.