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Critical severity9.8NVD Advisory· Published Mar 27, 2026· Updated Mar 31, 2026

CVE-2026-33937

CVE-2026-33937

Description

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.

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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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