Disclosure summary
Handlebars before 3.0.8 and 4.x before 4.5.3 is vulnerable to Arbitrary Code Execution. The lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript. This can be used to run arbitrary code on a server processing Handlebars templates or in a victim's browser (effectively serving as XSS).
Source-reported weakness categories
CWE-94
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2019-20920
Open original source · Updated Oct 08, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
| Vendor | Product / association | Version / bounds |
|---|---|---|
| handlebarsjs | handlebars | * {"versionStartIncluding":"4.0.0","versionEndExcluding":"4.5.3"} |
Original records & references
- NIST NVD record
- CVE Program record
- snyk.io — Third Party Advisory
- www.npmjs.com — Exploit, Third Party Advisory
- www.npmjs.com — Third Party Advisory
- snyk.io — Third Party Advisory
- www.npmjs.com — Exploit, Third Party Advisory
- www.npmjs.com — Third Party Advisory
PUBLISHED 2020-09-30T14:15:17-04:00
MODIFIED 2026-10-08T18:16:54-04:00
INGESTED 2026-10-10T20:50:19-04:00