CVE-2020-36632
CRITICALCVE-2020-36632 is a critical-severity (CVSS 9.8) CWE-1321 vulnerability in flat. O3 Security confirms whether CVE-2020-36632 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
flat vulnerable to Prototype Pollution
Blast Radius
flat📦flat📦flat📦flat📦flatReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
A vulnerability, which was classified as critical, was found in hughsk flat up to 5.0.0. This affects the function unflatten of the file index.js. The manipulation leads to improperly controlled modification of object prototype attributes ('prototype pollution'). It is possible to initiate the attack remotely. Upgrading to version 5.0.1 is able to address this issue. The name of the patch is 20ef0ef55dfa028caddaedbcb33efbdb04d18e13. It is recommended to upgrade the affected component. The identifier VDB-216777 was assigned to this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | flat | all versions | 1.6.2 |
| 📦npm | flat | ≥ 2.0.0&&< 2.0.2 | 2.0.2 |
| 📦npm | flat | ≥ 3.0.0&&< 3.0.1 | 3.0.1 |
| 📦npm | flat | ≥ 4.0.0&&< 4.0.2 | 4.0.2 |
| 📦npm | flat | ≥ 5.0.0&&< 5.0.1 | 5.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for flat. 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 flat to 1.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-36632 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-2020-36632 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-2020-36632. 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-2020-36632 in your dependencies?
O3 detects CVE-2020-36632 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.