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High severity8.2NVD Advisory· Published Mar 27, 2026· Updated Mar 31, 2026

CVE-2026-33941

CVE-2026-33941

Description

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.

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Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
handlebarsnpm
>= 4.0.0, < 4.7.94.7.9

Affected products

46

Patches

Vulnerability mechanics

References

5

News mentions

0

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