CVE-2026-59877: protobufjs Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j3f2-48v5-ccww",
  "modified" : "2026-07-20T22:03:00Z",
  "published" : "2026-07-20T22:03:00Z",
  "aliases" : [ "CVE-2026-59877" ],
  "summary" : "protobufjs: Denial of Service via infinite loop in .proto option parsing",
  "details" : "## Summary\n\nprotobufjs parsed option names by advancing through schema tokens until it reached an `=` token, without checking for end of input. A crafted `.proto` schema that opens an option declaration but ends prematurely could cause the option parser to loop without ever terminating.\n\nThis affects the reflection parsing path (`parse`, `Root.load`, `Root.loadSync`).\n\n## Impact\n\nAn attacker who can provide or influence `.proto` schema text parsed by an application may be able to cause the parsing call to never return. Because Node.js is single-threaded, the blocked event loop prevents all other work in the process, resulting in a denial of service that persists until the process is externally terminated.\n\nApplications that only encode or decode protobuf binary data with trusted schemas are not directly affected.\n\n## Preconditions\n\n- The application must parse `.proto` schema text influenced by an attacker.\n- The schema must be parsed through APIs such as `parse`, `Root.load`, or `Root.loadSync`.\n- The crafted input must begin an option declaration that ends before its `=` assignment.\n\n## Workarounds\n\nDo not parse `.proto` schemas from untrusted sources with affected versions. If untrusted schema text must be accepted, isolate parsing in a process or worker that can be safely terminated and bound it with a timeout, so a non-returning parse call cannot deny service to the rest of the application.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protobufjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.5.0"
      }, {
        "fixed" : "7.6.5"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 7.6.4"
    }
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protobufjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.6.6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 8.6.5"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59877"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/pull/2352"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/protobufjs/protobuf.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-20T22:03:00Z",
    "nvd_published_at" : "2026-07-08T16:16:34Z"
  }
}