Vulnerability Details CVE-2026-33937
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 48.2%
CVSS Severity
CVSS v3 Score 9.8
Products affected by CVE-2026-33937
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cpe:2.3:a:handlebarsjs:handlebars:4.0.0
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cpe:2.3:a:handlebarsjs:handlebars:4.0.1
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cpe:2.3:a:handlebarsjs:handlebars:4.0.10
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cpe:2.3:a:handlebarsjs:handlebars:4.0.11
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cpe:2.3:a:handlebarsjs:handlebars:4.0.12
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cpe:2.3:a:handlebarsjs:handlebars:4.0.13
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cpe:2.3:a:handlebarsjs:handlebars:4.0.13-0
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cpe:2.3:a:handlebarsjs:handlebars:4.0.14
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cpe:2.3:a:handlebarsjs:handlebars:4.0.2
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cpe:2.3:a:handlebarsjs:handlebars:4.0.3
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cpe:2.3:a:handlebarsjs:handlebars:4.0.4
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cpe:2.3:a:handlebarsjs:handlebars:4.0.5
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cpe:2.3:a:handlebarsjs:handlebars:4.0.6
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cpe:2.3:a:handlebarsjs:handlebars:4.0.7
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cpe:2.3:a:handlebarsjs:handlebars:4.0.8
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cpe:2.3:a:handlebarsjs:handlebars:4.0.9
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cpe:2.3:a:handlebarsjs:handlebars:4.1.0
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cpe:2.3:a:handlebarsjs:handlebars:4.1.1
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cpe:2.3:a:handlebarsjs:handlebars:4.1.2
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cpe:2.3:a:handlebarsjs:handlebars:4.1.2-0
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cpe:2.3:a:handlebarsjs:handlebars:4.2.0
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cpe:2.3:a:handlebarsjs:handlebars:4.2.1
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cpe:2.3:a:handlebarsjs:handlebars:4.2.2
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cpe:2.3:a:handlebarsjs:handlebars:4.3.0
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cpe:2.3:a:handlebarsjs:handlebars:4.3.1
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cpe:2.3:a:handlebarsjs:handlebars:4.3.2
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cpe:2.3:a:handlebarsjs:handlebars:4.3.3
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cpe:2.3:a:handlebarsjs:handlebars:4.3.4
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cpe:2.3:a:handlebarsjs:handlebars:4.3.5
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cpe:2.3:a:handlebarsjs:handlebars:4.4.0
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cpe:2.3:a:handlebarsjs:handlebars:4.4.1
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cpe:2.3:a:handlebarsjs:handlebars:4.4.2
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cpe:2.3:a:handlebarsjs:handlebars:4.4.3
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cpe:2.3:a:handlebarsjs:handlebars:4.4.4
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cpe:2.3:a:handlebarsjs:handlebars:4.4.5
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cpe:2.3:a:handlebarsjs:handlebars:4.5.0
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cpe:2.3:a:handlebarsjs:handlebars:4.5.1
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cpe:2.3:a:handlebarsjs:handlebars:4.5.2
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cpe:2.3:a:handlebarsjs:handlebars:4.5.3
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cpe:2.3:a:handlebarsjs:handlebars:4.6.0
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cpe:2.3:a:handlebarsjs:handlebars:4.7.0
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cpe:2.3:a:handlebarsjs:handlebars:4.7.1
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cpe:2.3:a:handlebarsjs:handlebars:4.7.2
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cpe:2.3:a:handlebarsjs:handlebars:4.7.3
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cpe:2.3:a:handlebarsjs:handlebars:4.7.4
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cpe:2.3:a:handlebarsjs:handlebars:4.7.5
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cpe:2.3:a:handlebarsjs:handlebars:4.7.6
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cpe:2.3:a:handlebarsjs:handlebars:4.7.7