---
id: CVE-2026-33937
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, `Handlebars.compile()` accepts a pre-parsed
  AST object in addition to a template string. The `value` field of a
  `NumberLitera…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-94
  - CWE-843
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-2026-33937'
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-2w6w-674q-4c4q
    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-2026-33937'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2452523'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33937.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-33937'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33937'
tags:
  - nvd
  - exploit-available
  - csaf
  - vex
  - red-hat
epss: 0.01907
epssPercentile: 0.7965
ingestedAt: '2026-07-02T12:34:40.401Z'
exploits:
  github: 4
  githubRepos:
    - 'https://github.com/dinhvaren/cve-2026-33937'
    - 'https://github.com/EQSTLab/CVE-2026-33937'
    - 'https://github.com/garlic-wizard/CVE-2026-33937-for-DarkZeroReturns'
  checkedAt: '2026-10-27T18:58:38.548Z'
exploitAvailable: true
---

## Overview

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `Handlebars.compile()` accepts a pre-parsed AST object in addition to a template string. The `value` field of a `NumberLiteral` AST node is emitted directly into the generated JavaScript without quoting or sanitization. An attacker who can supply a crafted AST to `compile()` can therefore inject and execute arbitrary JavaScript, leading to Remote Code Execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. Validate input type before calling `Handlebars.compile()`; ensure the argument is always a  `string`, never a plain object or JSON-deserialized value. Use the Handlebars runtime-only build (`handlebars/runtime`) on the server if templates are pre-compiled at build time; `compile()` will be unavailable.

## Affected

- `handlebars >= 4.0.0, < 4.7.9`

## Remediation

Upgrade past the affected range:

- `handlebars 4.7.9`

## Vendor advisories

- **RHSA-2026:34342** · Red Hat · fixed in: Cluster Observability Operator 1.5.3 · released 2026-07-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:34342)
- **RHSA-2026:10175** · Red Hat · fixed in: Red Hat OpenShift Dev Spaces 3.27 · released 2026-04-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:10175)
- **Red Hat VEX** · Important · affected: Logging Subsystem for Red Hat OpenShift, Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Logging Subsystem for Red Hat OpenShift, Red Hat Enterprise Linux 8, Red Hat Developer Hub, Red Hat Enterprise Linux 10, … · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33937.json)