---
id: CVE-2026-33941
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, the Handlebars CLI precompiler
  (`bin/handlebars` / `lib/precompiler.js`) concatenates user-controlled strings
  — template file…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H'
cwe:
  - CWE-79
  - CWE-94
  - CWE-116
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-2026-33941'
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-xjpj-3mr7-gcpf
    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-2026-33941'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2452524'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33941.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00291
epssPercentile: 0.21916
ingestedAt: '2026-07-02T12:34:40.439Z'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-03-31T00:00:00+00:00'
scores:
  nvd: 8.2
  cna: 8.3
---

## Overview

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, the Handlebars CLI precompiler (`bin/handlebars` / `lib/precompiler.js`) concatenates user-controlled strings — template file names and several CLI options — directly into the JavaScript it emits, without any escaping or sanitization. An attacker who can influence template filenames or CLI arguments can inject arbitrary JavaScript that executes when the generated bundle is loaded in Node.js or a browser. Version 4.7.9 fixes the issue. Some workarounds are available. First, validate all CLI inputs before invoking the precompiler. Reject filenames and option values  that contain characters with JavaScript string-escaping significance (`"`, `'`, `;`, etc.). Second, use a fixed, trusted namespace string passed via a configuration file rather than  command-line arguments in automated pipelines. Third, run the precompiler in a sandboxed environment (container with no write access to sensitive  paths) to limit the impact of successful exploitation. Fourth, audit template filenames in any repository or package that is consumed by an automated  build pipeline.

## Affected

- `handlebars >= 4.0.0, < 4.7.9`

## Remediation

Upgrade past the affected range:

- `handlebars 4.7.9`