CVE-2021-40893Public exploitNetwork attack vector

Service hang via inefficient email-validation regex

Published Jun 24, 2022 · Updated Aug 4, 2024

Regular expression denial of service in validate-data 0.1.1 allows remote attackers to hang Node.js services via crafted invalid emails. The email validator applies its regular expression to arbitrarily long attacker-controlled strings; a failing match incurs excessive backtracking and CPU time. A network endpoint that passes unbounded email input to the library exposes its Node.js process to unauthenticated service interruption.

CVSS severity7.5
High
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in validate-data 0.1.1 allows remote attackers to hang Node.js services via crafted invalid emails. The email validator applies its regular expression to arbitrarily long attacker-controlled strings; a failing match incurs excessive backtracking and CPU time. A network endpoint that passes unbounded email input to the library exposes its Node.js process to unauthenticated service interruption.

The record

CVE
CVE-2021-40893
Published
Jun 24, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1333, CAPEC-492, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CAPEC-492Regular Expression Exponential Blowup
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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