CVE-2021-32821: MooTools is a collection of JavaScript utilities for JavaScript developers

Q: How do I fix CVE-2021-32821?

mootools: upgrade to newer than 1.6.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-32821 being exploited?

CVE-2021-32821 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-2021-32821 affect?

CVE-2021-32821 affects mootools. Severity is medium (CVSS 6.2). MooTools is a collection of JavaScript utilities for JavaScript developers. All known versions include a CSS selector parser that is vulnerable to Regular Expression Denial of Service (ReDoS). An attack requires that an attacker can inject

Q: How urgent is CVE-2021-32821?

Priority 39/100. Public exploit reference

Routine

MEDIUM 6.2UPGRADE

CVE-2021-32821 is a medium-severity flaw (CVSS 6.2) affecting mootools. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MooTools is a collection of JavaScript utilities for JavaScript developers. All known versions include a CSS selector parser that is vulnerable to Regular Expression Denial of Service (ReDoS). An attack requires that an attacker can inject a string into a CSS selector at runtime, which is quite common with e.g. jQuery CSS selectors. No patches are available for this issue.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.2 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 49%)
CISA exploited list	No
Weakness	CWE-400, CWE-1333
Published	2023-01-03
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: mootools

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

Am I affected?

Timeline

2023-01-03 17:15 UTCPublished CVE record published
2026-06-17 03:53 UTCUpdated Record last modified

mootools mootools UPGRADE

Affected: <= 1.6.0

Fixed in: newer than 1.6.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy mootools || rpm -q mootools || mootools --version

2. UPGRADE to newer than 1.6.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mootools

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mootools

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-2021-32821?

mootools: upgrade to newer than 1.6.0. Exact commands for each OS are on this page.

Is CVE-2021-32821 being exploited?

CVE-2021-32821 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-2021-32821 affect?

CVE-2021-32821 affects mootools. Severity is medium (CVSS 6.2). MooTools is a collection of JavaScript utilities for JavaScript developers. All known versions include a CSS selector parser that is vulnerable to Regular Expression Denial of Service (ReDoS). An attack requires that an attacker can inject

How urgent is CVE-2021-32821?

Priority 39/100. Public exploit reference

Software pages

jQuery vulnerabilities

References

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