CVE-2020-15256 is a critical-severity (CVSS 9.8) Improper Input Validation vulnerability in object-path. O3 Security confirms whether CVE-2020-15256 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Prototype pollution in object-path
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-2020-15256 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 0 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.
object-pathnpmDescription
A prototype pollution vulnerability has been found in object-path <= 0.11.4 affecting the set() method. The vulnerability is limited to the includeInheritedProps mode (if version >= 0.11.0 is used), which has to be explicitly enabled by creating a new instance of object-path and setting the option includeInheritedProps: true, or by using the default withInheritedProps instance. The default operating mode is not affected by the vulnerability if version >= 0.11.0 is used. Any usage of set() in versions < 0.11.0 is vulnerable. The issue is fixed in object-path version 0.11.5 As a workaround, don't use the includeInheritedProps: true options or the withInheritedProps instance if using a version >= 0.11.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | object-path | all versions | 0.11.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for object-path. 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 object-path to 0.11.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15256 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-2020-15256 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-2020-15256. 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.
Frequently Asked Questions
Is CVE-2020-15256 in your dependencies?
O3 detects CVE-2020-15256 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.