handlebars-lang Handlebars up to 4.7.9 AST Validation Handlebars.compile/Handlebars.precompile code injection

Summaryinfo

A vulnerability categorized as critical has been discovered in handlebars-lang Handlebars up to 4.7.9. This issue affects the function Handlebars.compile/Handlebars.precompile of the component AST Validation. Such manipulation leads to code injection. This vulnerability is documented as CVE-2026-106446. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in handlebars-lang Handlebars up to 4.7.9. Affected by this issue is the function Handlebars.compile/Handlebars.precompile of the component AST Validation. The manipulation with an unknown input leads to a code injection vulnerability. Using CWE to declare the problem leads to CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars.compile() and Handlebars.precompile() accept pre-parsed AST objects while validating only selected PathExpression, NumberLiteral, and BooleanLiteral values. This issue bypasses the AST validation introduced in version 4.7.9 for CVE-2026-33937. An attacker who can supply an object instead of a template string can place JavaScript expressions in unchecked values such as Program.blockParams.length, a non-PathExpression parameter depth, a non-string StringLiteral.value, or a non-string PathExpression.original. The compiler emits those values into generated JavaScript, causing code execution in the server process when compile output renders or wherever precompile output is loaded. Applications that pass only template strings are not affected. This issue is fixed in version 4.7.10.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-106446 since 10/06/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059 by the MITRE ATT&CK project.

Upgrading to version 4.7.10 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• handlebars-lang

Name

• Handlebars

Version

• 4.7.0
• 4.7.1
• 4.7.2
• 4.7.3
• 4.7.4
• 4.7.5
• 4.7.6
• 4.7.7
• 4.7.8
• 4.7.9

CPE 2.3info

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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