How severe is CVE-2020-28500?

CVE-2020-28500 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-28500?

CVE-2020-28500 affects the following packages: lodash (npm), lodash-es (npm), lodash.trimend (npm), lodash.trim (npm), lodash-rails (RubyGems). Ecosystems affected: npm, RubyGems.

How do I fix CVE-2020-28500?

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.

How do I detect CVE-2020-28500 in my npm, RubyGems dependencies?

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.

How do I mitigate CVE-2020-28500 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2020-28500?

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.

Is CVE-2020-28500 actively exploited in the wild?

Yes. There are 6 known exploit references for CVE-2020-28500, including 6 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-28500?

CVE-2020-28500 has an EPSS (Exploit Prediction Scoring System) score of 7.3%, placing it in the 94th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2020-28500 published, and has it been updated?

CVE-2020-28500 was published on February 15, 2021 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm💎 RubyGems

CVE-2020-28500

MEDIUM

Regular Expression Denial of Service (ReDoS) in lodash

Also known asGHSA-29mw-wpgm-hmr9

Published

Feb 15, 2021

Updated

Jul 8, 2026

Affected

5 pkgs

Patched

3 / 5

Exploits

6 known

EPSS Exploitation Probability

via FIRST.org ↗

7.3%probability of exploitation in next 30 days

Lower Risk94th percentile0.00%

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.

Blast Radius

5 pkgs affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

lodashnpm

163.6Mdownloads / week

lodash-esnpm

42.0Mdownloads / week

lodash.trimendnpm

116Kdownloads / week

Description

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

5 total 3 fixed

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

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.