Vulnerabilities in pkg:npm/locutus

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rxrv-835q-v5mh",
  "modified" : "2026-10-05T15:34:16Z",
  "published" : "2026-02-02T22:21:54Z",
  "aliases" : [ "CVE-2026-25521" ],
  "summary" : "locutus is vulnerable to Prototype Pollution",
  "details" : "### Summary\nA Prototype Pollution vulnerability exists in the the npm package locutus (>2.0.12). Despite a previous fix that attempted to mitigate Prototype Pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using String.prototype. This issue was fixed in version 2.0.39.\n\n### Details\nThe vulnerability resides in line 77 to 79 of https://github.com/locutusjs/locutus/blob/main/src/php/strings/parse_str.js where includes() function is used to check whether user provided input contain forbidden strings.\n\n### PoC\n\n#### Steps to reproduce\n1. Install latest version of locutus using npm install or cloning from git\n2. Run the following code snippet:\n\n```javascript\nString.prototype.includes = () => false;      \nconsole.log({}.polluted);\nconst locutus = require('locutus');\nlocutus.php.strings.parse_str('constructor[prototype][polluted]=yes');\nconsole.log({}.polluted);  // prints yes -> indicating that the patch was bypassed and Prototype Pollution occurred\n```\n\n#### Expected behavior\nPrototype Pollution should be prevented and {} should not gain new properties.\nThis should be printed on the console:\n```\nundefined\nundefined OR throw an Error\n```\n\n#### Actual behavior\nObject.prototype is polluted\nThis is printed on the console:\n```\nundefined \nyes\n```\n\n### Impact\nThis is a Prototype Pollution vulnerability, which can have severe security implications depending on how locutus is used by downstream applications. Any application that processes attacker-controlled input using this `locutus.php.strings.parse_str` may be affected. It could potentially lead to the following problems:\n1. Authentication bypass\n2. Denial of service\n3. Remote code execution (if polluted property is passed to sinks like eval or child_process)",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "locutus"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.12"
      }, {
        "fixed" : "2.0.39"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/locutusjs/locutus/security/advisories/GHSA-rxrv-835q-v5mh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-25521"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/locutusjs/locutus/commit/042af9ca7fde2ff599120783e720a17f335bb01c"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-25521"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2436950"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/locutusjs/locutus"
  }, {
    "type" : "WEB",
    "url" : "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25521.json"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-02T22:21:54Z",
    "nvd_published_at" : "2026-02-04T22:15:59Z"
  }
}