CVE-2020-26302: is.js is a general-purpose check library

Q: How do I fix CVE-2020-26302?

is.js: upgrade to newer than 0.9.0. Exact commands for each OS are on this page.

Q: Is CVE-2020-26302 being exploited?

CVE-2020-26302 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-26302 affect?

CVE-2020-26302 affects is.js. Severity is high (CVSS 7.5). is.js is a general-purpose check library. Versions 0.9.0 and prior contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). is.js uses a regex copy-pasted from a gist to validate URLs. Try

Q: How urgent is CVE-2020-26302?

Priority 51/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2020-26302 is a high-severity flaw (CVSS 7.5) affecting is.js. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

is.js is a general-purpose check library. Versions 0.9.0 and prior contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). is.js uses a regex copy-pasted from a gist to validate URLs. Trying to validate a malicious string can cause the regex to loop “forever." This vulnerability was found using a CodeQL query which identifies inefficient regular expressions. is.js has no patch for this issue.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-400, CWE-1333
Published	2022-12-22
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: is.js project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-12-22 21:15 UTCPublished CVE record published
2026-06-17 03:08 UTCUpdated Record last modified

is.js project is.js UPGRADE

Affected: <= 0.9.0

Fixed in: newer than 0.9.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy is.js || rpm -q is.js || is.js --version

2. UPGRADE to newer than 0.9.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade is.js

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade is.js

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-26302?

is.js: upgrade to newer than 0.9.0. Exact commands for each OS are on this page.

Is CVE-2020-26302 being exploited?

CVE-2020-26302 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-26302 affect?

CVE-2020-26302 affects is.js. Severity is high (CVSS 7.5). is.js is a general-purpose check library. Versions 0.9.0 and prior contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). is.js uses a regex copy-pasted from a gist to validate URLs. Try

How urgent is CVE-2020-26302?

Priority 51/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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