cve-2026-33937

CRITICAL CVSS 9.8 nvd
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.

Timeline
Published
2026-03-27
Last Modified
2026-10-26
CVSS Details
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
Affected Products
  • handlebarsjs handlebars
Weaknesses (CWE)
CWE-94 CWE-843
CVSS metrics
Version Base Severity Vector Exploitability Impact Source
3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 3.9 5.9 security-advisories@github.com
3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 3.9 5.9 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
CPE configurations
OR
CPE Version range Vulnerable
cpe:2.3:a:handlebarsjs:handlebars:*:*:*:*:*:node.js:*:* >= 4.0.0, < 4.7.9 yes
NVD metadata
NVD status
Modified
Source identifier
security-advisories@github.com
References
Linked Vulnerabilities
cpuoct2026csaf csaf_oracle 

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  "dateUpdated": "2026-10-26T22:10:00.163",
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        "value": "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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  "source": "nvd",
  "title": "Handlebars provides the power necessary to let users build semantic templates"
}
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