CVE-2016-3956
HIGHCVE-2016-3956 is a high-severity (CVSS 7.5) Information Exposure vulnerability in npm. O3 Security confirms whether CVE-2016-3956 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
npm Token Leak in npm
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
npmnpmDescription
The CLI in npm before 2.15.1 and 3.x before 3.8.3, as used in Node.js 0.10 before 0.10.44, 0.12 before 0.12.13, 4 before 4.4.2, and 5 before 5.10.0, includes bearer tokens with arbitrary requests, which allows remote HTTP servers to obtain sensitive information by reading Authorization headers.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | npm | all versions | 2.15.1 |
| 📦npm | npm | ≥ 3.0.0&&< 3.8.3 | 3.8.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for npm. 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 npm to 2.15.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-3956 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-2016-3956 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-2016-3956. 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-2016-3956 in your dependencies?
O3 detects CVE-2016-3956 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.