CVE-2021-36716
HIGHCVE-2021-36716 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in is-email. O3 Security confirms whether CVE-2021-36716 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Improper Input Validation in is-email
Real-World Exposure
is-emailReal-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
is-email helps validate an email address. A ReDoS (regular expression denial of service) flaw was found in the Segment is-email package before 1.0.1 for Node.js. An attacker that is able to provide crafted input to the isEmail(input) function may cause an application to consume an excessive amount of CPU.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | is-email | all versions | 1.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for is-email. 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 is-email to 1.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-36716 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-2021-36716 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-2021-36716. 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-2021-36716 in your dependencies?
O3 detects CVE-2021-36716 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.