CVE-2022-21195Network attack vector

Service interruption via inefficient URL matching

Published May 20, 2022 · Updated Sep 16, 2024

Regular expression denial of service in AlexFlipnote url-regex 1.0.4 and earlier allows remote attackers to interrupt service via crafted URL text. The URL-matching expression performs computationally inefficient matching on maliciously structured input, consuming excessive CPU time. Any application that passes attacker-controlled text to the library can have its processing thread monopolized, while confidentiality and integrity remain unaffected.

CVSS severity7.5
High
EPSS probability1.34%
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 AlexFlipnote url-regex 1.0.4 and earlier allows remote attackers to interrupt service via crafted URL text. The URL-matching expression performs computationally inefficient matching on maliciously structured input, consuming excessive CPU time. Any application that passes attacker-controlled text to the library can have its processing thread monopolized, while confidentiality and integrity remain unaffected.

The record

CVE
CVE-2022-21195
Published
May 20, 2022
Updated
Sep 16, 2024
Vendor
Kevin Mårtensson
Product
url-regex
Classifications
CWE-1333, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 20, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kevin Mårtensson · url-regexversion=0 <unspecified

Published CVSS scores

5.3SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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