CVE-2026-33916
Handlebars.js has Prototype Pollution Leading to XSS through Partial Template Injection
At a glance
- Source
- NVD
- EPSS
- EPSS 0.28 % · percentile 20 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which does not compile templates and reduces the attack surface.
Weaknesses (CWE)
- CWE-79 — Cross-site Scripting (XSS)
- CWE-1321 — Improperly Controlled Modification of Object Prototype (Prototype Pollution)
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 4.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N | GitHub_M |
| CVSS 3.1 | MEDIUM 4.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 4.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-2qvq-rjwj-gvw9 — Handlebars.js has Prototype Pollution Leading to XSS through Partial Template Injection
European references
- ENISA EUVD · EUVD-2026-16847
- GCVE · GCVE-0-2026-33916
CERT-FR advisories
- CERTFR-2026-AVI-1032 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0667 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0581 — Multiples vulnérabilités dans MongoDB · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:handlebarsjs:handlebars:*:*:*:*:*:node.js:*:*≥ 4.0.0 < 4.7.9
Affected products
| Product | Versions |
|---|---|
| handlebars-lang · handlebars.js | affected >= 4.0.0, < 4.7.9 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |