CVE-2026-44292: Protobufjs Prototype Injection Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fx83-v9x8-x52w",
  "modified" : "2026-05-14T20:35:19Z",
  "published" : "2026-05-12T15:01:44Z",
  "aliases" : [ "CVE-2026-44292" ],
  "summary" : "protobuf.js: Prototype injection in generated message constructors",
  "details" : "## Summary\n\nprotobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the `__proto__` key. If an application constructed a message from an attacker-controlled plain object, an own enumerable `__proto__` property could alter the prototype of that individual message instance.\n\n## Impact\n\nAn attacker who can control the properties object passed to a generated protobufjs message constructor or creation helper may be able to modify the prototype chain of the resulting message instance.\n\nThis is a per-instance prototype injection issue. It does not pollute `Object.prototype` or other global prototypes. The impact depends on downstream application behavior, such as relying on inherited properties, prototype methods, or `instanceof` checks for message objects.\n\nApplications that only decode binary protobuf data, or that construct messages from trusted application-defined objects, are not directly affected by this issue.\n\n## Preconditions\n\n- The application must allow an attacker to control or influence a plain object used to construct a protobufjs message.\n- The object must contain an own enumerable `__proto__` property, for example from parsed JSON input.\n- The application must pass that object to a generated message constructor or creation helper that copies arbitrary enumerable properties.\n\n## Workarounds\n\nDo not pass attacker-controlled plain objects directly to generated message constructors with affected versions. If untrusted JSON input must be accepted, validate or sanitize object keys before constructing messages, and reject `__proto__` properties.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protobufjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.5.6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 7.5.5"
    }
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protobufjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 8.0.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-fx83-v9x8-x52w"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44292"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/protobufjs/protobuf.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.5.6"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.0.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-12T15:01:44Z",
    "nvd_published_at" : "2026-05-13T16:16:56Z"
  }
}