Regular expression Denial of Service in MooTools
Priority HIGH 66CWE-400Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-400.
Summary
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 it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00675 52nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| mootools | mootools-core | 1.6.0 – 1.6.0 | — | No fix listed | CNA |
| — | mootools (npm) | up to 1.5.2 | — | No fix listed | GHSA-v63q-hgqc-qvpg |
- mootools-core Vendormootools Affected 1.6.0 – 1.6.0 Fixed in — No fix listed CNA
- mootools (npm) Vendor— Affected up to 1.5.2 Fixed in — No fix listed GHSA-v63q-hgqc-qvpg
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-32821
- 2026-10-03 Alias added: GHSA-v63q-hgqc-qvpg
- 2026-10-16 EPSS moved to the 50th–90th percentile
References
Sources
- CVE-2021-32821 · CVE Program
- CVE-2021-32821 · NVD
- FIRST EPSS
- GHSA-v63q-hgqc-qvpg · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences