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GHSA-JG82-XH3W-RHXX

Vulnerability from github – Published: 2023-10-18 18:27 – Updated: 2025-07-22 15:37
VLAI
Summary
Synchrony deobfuscator prototype pollution vulnerability leading to arbitrary code execution
Details

Impact

A __proto__ pollution vulnerability exists in synchrony versions before v2.4.4. Successful exploitation could lead to arbitrary code execution.

Summary

A __proto__ pollution vulnerability exists in the LiteralMap transformer allowing crafted input to modify properties in the Object prototype.

When executing in Node.js, due to use of the prettier module, defining a parser property on __proto__ with a path to a JS module on disk causes a require of the value which can lead to arbitrary code execution.

Patch

A fix has been released in deobfuscator@2.4.4.

Mitigation

Proof of Concept

Craft a malicious input file named poc.js as follows:

// Malicious code to be run after this file is imported. Logs the result of shell command "dir" to the console.
console.log(require('child_process').execSync('dir').toString())

// Synchrony exploit PoC
{
  var __proto__ = { parser: 'poc.js' }
}

Then, run synchrony poc.js from the same directory as the malicious file.

Credits

This vulnerability was found and disclosed by William Khem-Marquez.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "deobfuscator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.1"
            },
            {
              "fixed": "2.4.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2023-45811"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-10-18T18:27:13Z",
    "nvd_published_at": "2023-10-17T23:15:12Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nA `__proto__` pollution vulnerability exists in synchrony versions before v2.4.4. Successful exploitation could lead to arbitrary code execution.\n\n### Summary\n\nA `__proto__` pollution vulnerability exists in the [LiteralMap] transformer allowing crafted input to modify properties in the Object prototype.\n\nWhen executing in Node.js, due to use of the `prettier` module, defining a `parser` property on `__proto__` with a path to a JS module on disk [causes a `require` of the value][prettier/src/main/parser.js] which can lead to arbitrary code execution.\n\n### Patch\n\nA fix has been released in `deobfuscator@2.4.4`.\n\n### Mitigation\n\n- Upgrade synchrony to v2.4.4\n- Launch node with the [--disable-proto=delete][disable-proto] or [--disable-proto=throw][disable-proto] flag\n\n### Proof of Concept\n\nCraft a malicious input file named `poc.js` as follows:\n\n```js\n// Malicious code to be run after this file is imported. Logs the result of shell command \"dir\" to the console.\nconsole.log(require(\u0027child_process\u0027).execSync(\u0027dir\u0027).toString())\n\n// Synchrony exploit PoC\n{\n  var __proto__ = { parser: \u0027poc.js\u0027 }\n}\n```\n\nThen, run `synchrony poc.js` from the same directory as the malicious file.\n\n### Credits\n\nThis vulnerability was found and disclosed by [William Khem-Marquez][SteakEnthusiast].\n\n[LiteralMap]: src/transformers/literalmap.ts\n[SteakEnthusiast]: https://github.com/SteakEnthusiast\n[disable-proto]: https://nodejs.dev/en/api/v20/cli/#--disable-protomode\n[prettier/src/main/parser.js]: https://github.com/prettier/prettier/blob/2.5.1/src/main/parser.js#L53-L63",
  "id": "GHSA-jg82-xh3w-rhxx",
  "modified": "2025-07-22T15:37:30Z",
  "published": "2023-10-18T18:27:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/relative/synchrony/security/advisories/GHSA-jg82-xh3w-rhxx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-45811"
    },
    {
      "type": "WEB",
      "url": "https://github.com/relative/synchrony/commit/b583126be94c4db7c5a478f1c5204bfb4162cf40"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/relative/synchrony"
    },
    {
      "type": "WEB",
      "url": "https://github.com/relative/synchrony/security/advisories/src/transformers/literalmap.ts"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Synchrony deobfuscator prototype pollution vulnerability leading to arbitrary code execution"
}



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