GHSA-f23m-r3pf-42rh
MEDIUMGHSA-f23m-r3pf-42rh is a medium-severity (CVSS 6.5) CWE-1321 vulnerability in lodash. O3 Security confirms whether GHSA-f23m-r3pf-42rh is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
lodash vulnerable to Prototype Pollution via array path bypass in `_.unset` and `_.omit`
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
lodashnpmlodash-esnpmlodash-amdnpmDescription
Impact
Lodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the _.unset and _.omit functions. The fix for CVE-2025-13465 only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as Object.prototype, Number.prototype, and String.prototype.
The issue permits deletion of prototype properties but does not allow overwriting their original behavior.
Patches
This issue is patched in 4.18.0.
Workarounds
None. Upgrade to the patched version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | lodash | all versions | 4.18.0 |
| 📦npm | lodash-es | all versions | 4.18.0 |
| 📦npm | lodash-amd | all versions | 4.18.0 |
| 📦npm | lodash.unset | ≥ 4.0.0&&< 4.18.0 | 4.18.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lodash. 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 lodash to 4.18.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f23m-r3pf-42rh 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 GHSA-f23m-r3pf-42rh 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 GHSA-f23m-r3pf-42rh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-f23m-r3pf-42rh in your dependencies?
O3 detects GHSA-f23m-r3pf-42rh across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.