CVE-2020-7661Public exploitNetwork attack vector

Process hang via excessive regular-expression backtracking

Published Jun 4, 2020 · Updated Aug 4, 2024

Regular expression denial of service in url-regex 5.0.0 and earlier allows attackers to hang a JavaScript process via crafted input. The RegExp returned with strict:false performs excessive backtracking against a long numeric, dot-delimited non-URL string passed to RegExp.test(), driving CPU usage to 100% without completing. Any application that tests attacker-controlled strings with the affected expression can have its event loop blocked, while applications that do not expose such input are not remotely reachable through the library alone.

CVSS severity7.5
High
EPSS probability2.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Regular expression denial of service in url-regex 5.0.0 and earlier allows attackers to hang a JavaScript process via crafted input. The RegExp returned with strict:false performs excessive backtracking against a long numeric, dot-delimited non-URL string passed to RegExp.test(), driving CPU usage to 100% without completing. Any application that tests attacker-controlled strings with the affected expression can have its event loop blocked, while applications that do not expose such input are not remotely reachable through the library alone.

The record

CVE
CVE-2020-7661
Published
Jun 4, 2020
Updated
Aug 4, 2024
Vendor
Kevin Mårtensson
Product
url-regex
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2020CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=all versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kevin Mårtensson · url-regexversion=all versions

Published CVSS scores

7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo