---
id: CVE-2026-33939
title: Handlebars provides the power necessary to let users build semantic templates
summary: >-
  Handlebars provides the power necessary to let users build semantic templates.
  In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator
  syntax referencing an unregistered decorator (e.g. `{{*n}}`), the compiled
  temp…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-754
  - CWE-248
vendor: handlebarsjs
product: handlebars
affected:
  - 'handlebars >= 4.0.0, < 4.7.9'
patched:
  - handlebars 4.7.9
published: '2026-03-27'
updated: '2026-07-02'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33939'
references:
  - url: >-
      https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2
    label: security-advisories@github.com
  - url: 'https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9'
    label: security-advisories@github.com
  - url: >-
      https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:10175'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:34342'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-33939'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2452508'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33939.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00757
epssPercentile: 0.53259
ingestedAt: '2026-07-02T12:34:40.408Z'
---

## Overview

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. `{{*n}}`), the compiled template calls `lookupProperty(decorators, "n")`, which returns `undefined`. The runtime then immediately invokes the result as a function, causing an unhandled `TypeError: ... is not a function` that crashes the Node.js process. Any application that compiles user-supplied templates without wrapping the call in a `try/catch` is vulnerable to a single-request Denial of Service. Version 4.7.9 fixes the issue. Some workarounds are available. Wrap compilation and rendering in `try/catch`. Validate template input before passing it to `compile()`; reject templates containing  decorator syntax (`{{*...}}`) if decorators are not used in your application. Use the pre-compilation workflow; compile templates at build time and serve only pre-compiled  templates; do not call `compile()` at request time.

## Affected

- `handlebars >= 4.0.0, < 4.7.9`

## Remediation

Upgrade past the affected range:

- `handlebars 4.7.9`