{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "6.6.0"
              },
              {
                "fixed": "6.6.10"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "791aa58f4c0a003335a945fdd704cb910bd35970"
            },
            {
              "fixed": "86db1fc3db2cd315a065d64c4e48918ccf9b4729"
            },
            {
              "fixed": "64066c367386b3eb96677479a8978d6a8230c5ee"
            }
          ],
          "repo": "https://github.com/socketio/socket.io",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-2gc4-cqfq-p2gv"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-248"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102599.json"
  },
  "details": "Socket.IO enables bidirectional and low-latency communication for every platform. From Engine.IO 6.6.0 until 6.6.10, a transport upgrade can independently derive an Engine.IO protocol revision from the upgrade request instead of enforcing the revision stored on the existing session. A malicious client can establish a valid session and send an upgrade request with a different or omitted EIO query parameter, attaching a transport with incompatible parser and heartbeat behavior. A crafted heartbeat packet can then trigger an uncaught exception and terminate the Node.js process, including when Engine.IO v3 compatibility is disabled because an omitted EIO value is interpreted as revision 3 on the affected path. This issue is fixed in Engine.IO 6.6.10.",
  "id": "CVE-2026-102599",
  "modified": "2026-10-17T10:30:42.787033220Z",
  "published": "2026-10-13T19:05:10.870Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.10"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102599.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/socketio/socket.io/security/advisories/GHSA-2gc4-cqfq-p2gv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102599"
    },
    {
      "type": "FIX",
      "url": "https://github.com/socketio/socket.io/commit/86db1fc3db2cd315a065d64c4e48918ccf9b4729"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Socket.IO: Engine.IO Protocol Revision Mismatch DoS"
}