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Not in CISA KEV
HIGH severity

CVE-2021-36716 — is-email

HIGH

CVE-2021-36716 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in is-email. A fix is available for is-email — see the affected versions and patch details below.

Improper Input Validation in is-email

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.0%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs61th percentile — riskier than 61% of all scored CVEsHighest risk
0.00%0.50%0.99%1.49%0.5%1.0%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-36716 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

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.

63other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
is-emailnpm
55Kdownloads / week

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

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmis-emailall versions1.0.1npm install is-email@1.0.1

Affected Products

1 product · 1 configurations
Application
is-emailsegment
< 1.0.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for is-email, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. 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.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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