{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "0"
              },
              {
                "fixed": "3.0.25"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0d2402bdb92f9c59918114af9c8ba628f22e9152"
            }
          ],
          "repo": "https://github.com/locutusjs/locutus",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-4mph-v827-f877"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-1321"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33993.json"
  },
  "details": "Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. Prior to version 3.0.25, the `unserialize()` function in `locutus/php/var/unserialize` assigns deserialized keys to plain objects via bracket notation without filtering the `__proto__` key. When a PHP serialized payload contains `__proto__` as an array or object key, JavaScript's `__proto__` setter is invoked, replacing the deserialized object's prototype with attacker-controlled content. This enables property injection, for...in propagation of injected properties, and denial of service via built-in method override. This is distinct from the previously reported prototype pollution in `parse_str` (GHSA-f98m-q3hr-p5wq, GHSA-rxrv-835q-v5mh) — `unserialize` is a different function with no mitigation applied. Version 3.0.25 patches the issue.",
  "id": "CVE-2026-33993",
  "modified": "2026-04-01T23:10:03.411584730Z",
  "published": "2026-03-27T22:14:03.495Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33993.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/locutusjs/locutus/commit/345a6211e1e6f939f96a7090bfeff642c9fcf9e4"
    },
    {
      "type": "FIX",
      "url": "https://github.com/locutusjs/locutus/pull/597"
    },
    {
      "type": "WEB",
      "url": "https://github.com/locutusjs/locutus/releases/tag/v3.0.25"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/locutusjs/locutus/security/advisories/GHSA-4mph-v827-f877"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33993"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Locutus has Prototype Pollution via __proto__ Key Injection in unserialize()"
}