CVE-2021-4299Network attack vector

Application denial of service via naturalSort regex

Published Jan 2, 2023 · Updated Aug 3, 2024

Regular expression denial of service in Cronvel String Kit 0.12.7 and earlier allows remote attackers to interrupt applications. The naturalSort function in lib/naturalSort.js tokenizes attacker-controlled sort values with a complex regular expression whose backtracking consumes excessive CPU. Reachability requires a consuming Node.js application to pass remotely supplied values into naturalSort, where processing can monopolize the event loop and interrupt that application.

CVSS severity4.3
Medium
EPSS probability0.93%
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 Cronvel String Kit 0.12.7 and earlier allows remote attackers to interrupt applications. The naturalSort function in lib/naturalSort.js tokenizes attacker-controlled sort values with a complex regular expression whose backtracking consumes excessive CPU. Reachability requires a consuming Node.js application to pass remotely supplied values into naturalSort, where processing can monopolize the event loop and interrupt that application.

The record

CVE
CVE-2021-4299
Published
Jan 2, 2023
Updated
Aug 3, 2024
Vendor
Cronvel
Product
String Kit
Classifications
CWE-1333, CAPEC-492, T1499.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.12.0
  2. Affected versionversion=0.12.1
  3. Affected versionversion=0.12.2
  4. Affected versionversion=0.12.3
  5. Affected versionversion=0.12.4
  6. Affected versionversion=0.12.5
  7. Affected versionversion=0.12.6
  8. Affected versionversion=0.12.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cronvel · String Kitversion=0.12.0; version=0.12.1; version=0.12.2; version=0.12.3; version=0.12.4; version=0.12.5; version=0.12.6; version=0.12.7

Published CVSS scores

4.0VulDBAV:N/AC:L/Au:S/C:N/I:N/A:P
4.3VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CAPEC-492Regular Expression Exponential Blowup
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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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