CVE-2020-28500 is a medium-severity (CVSS 5.3) vulnerability in lodash. 6 public exploit references exist, so weaponization risk is real. O3 Security confirms whether CVE-2020-28500 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Regular Expression Denial of Service (ReDoS) in lodash
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-2020-28500 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 368,770 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.
lodashnpmlodash-esnpmlodash.trimendnpmDescription
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression Denial of Service (ReDoS) via the toNumber, trim and trimEnd functions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | lodash | ≥ 4.0.0&&< 4.17.21 | 4.17.21 |
| 📦npm | lodash-es | ≥ 4.0.0&&< 4.17.21 | 4.17.21 |
| 📦npm | lodash.trimend | ≥ 4.0.0 | No fix |
| 📦npm | lodash.trim | ≥ 4.0.0 | No fix |
| 💎RubyGems | lodash-rails | ≥ 4.0.0&&< 4.17.21 | 4.17.21 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression De…
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression De…
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression De…
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression De…
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression De…
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression De…
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 4.17.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-28500 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-2020-28500 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-2020-28500. 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.
In OpenShift ServiceMesh (OSSM) and Red Hat OpenShift Jaeger (RHOSJ) the affected containers are behind OpenShift OAuth authentication. This restricts access to the vulnerable nodejs-lodash library to authenticated users only, therefore the impact is low. While Red Hat Virtualization's cockpit-ovirt has a dependency…
Frequently Asked Questions
Is CVE-2020-28500 in your dependencies?
O3 detects CVE-2020-28500 across npm, RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.