Plateforme
nodejs
Composant
handlebars
Corrigé dans
4.0.1
CVE-2026-33941 is a high-severity vulnerability affecting Handlebars.js versions 4.0.0 through 4.7.8. This vulnerability arises from the unsafe concatenation of user-controlled data, such as template filenames and command-line options, directly into the JavaScript code generated by the Handlebars CLI precompiler. Successful exploitation can lead to arbitrary JavaScript code execution within the context of the application, potentially compromising sensitive data and system integrity.
An attacker exploiting CVE-2026-33941 can inject malicious JavaScript code into the Handlebars.js bundle. This code will execute when the bundle is loaded in either a Node.js environment or a web browser. The impact of this code execution depends on the privileges of the application and the environment. In a Node.js server, an attacker could potentially gain control of the server, access sensitive data stored on the server, or even execute arbitrary commands on the system. In a browser environment, an attacker could steal user credentials, redirect users to malicious websites, or deface the website.
CVE-2026-33941 was publicly disclosed on March 27, 2026. While no active exploitation campaigns have been confirmed, the vulnerability's ease of exploitation and the widespread use of Handlebars.js make it a potential target. The vulnerability is not currently listed on CISA's KEV catalog. Public proof-of-concept exploits are likely to emerge, increasing the risk of exploitation.
Applications using Handlebars.js for templating in Node.js environments or web browsers are at risk. This includes projects that rely on the Handlebars CLI precompiler for build processes. Shared hosting environments where multiple applications share the same Node.js installation are particularly vulnerable, as an attacker could potentially compromise one application and use it to attack others.
• nodejs / supply-chain:
Get-Process | Where-Object {$_.ProcessName -like '*handlebars*'} | Select-Object Name, Id, Path• nodejs / server:
journalctl -u node -f | grep -i "handlebars"• generic web:
curl -I https://example.com/bundle.js | grep Content-Typedisclosure
Statut de l'Exploit
EPSS
0.02% (percentile 5%)
CISA SSVC
Vecteur CVSS
The primary mitigation for CVE-2026-33941 is to upgrade Handlebars.js to version 4.7.9 or later, which includes a fix for the vulnerability. If upgrading is not immediately feasible, consider implementing workarounds. Validate all template filenames and command-line arguments before they are used in the precompilation process. This validation should ensure that the input is safe and does not contain any malicious code. Input sanitization and escaping are crucial. After upgrading, confirm the fix by attempting to precompile a template with a deliberately malicious filename; the precompiler should reject the attempt with an error.
Actualice a la versión 4.7.9 o superior de Handlebars.js. Como alternativa, valide las entradas de la CLI, use un espacio de nombres confiable, ejecute el precompilador en un entorno aislado o audite los nombres de archivo de plantilla.
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CVE-2026-33941 is a high-severity vulnerability in Handlebars.js versions 4.0.0–4.7.8 that allows an attacker to inject arbitrary JavaScript code by manipulating template filenames or CLI arguments.
You are affected if you are using Handlebars.js versions 4.0.0 through 4.7.8 and are using the CLI precompiler. Check your project dependencies and update accordingly.
Upgrade Handlebars.js to version 4.7.9 or later. As a temporary workaround, validate all template filenames and CLI arguments before precompilation.
While no active exploitation campaigns have been confirmed, the vulnerability's ease of exploitation makes it a potential target. Monitor for emerging proof-of-concept exploits.
Refer to the Handlebars.js project's security advisories and release notes on their official website or GitHub repository.
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