{"id":"CVE-2026-102599","summary":"Socket.IO: Engine.IO Protocol Revision Mismatch DoS","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.","aliases":["GHSA-2gc4-cqfq-p2gv"],"modified":"2026-10-15T02:47:17.859411336Z","published":"2026-10-13T19:05:10.870Z","database_specific":{"cwe_ids":["CWE-248"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102599.json","cna_assigner":"GitHub_M"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/socketio/socket.io","events":[{"introduced":"791aa58f4c0a003335a945fdd704cb910bd35970"},{"fixed":"86db1fc3db2cd315a065d64c4e48918ccf9b4729"},{"fixed":"64066c367386b3eb96677479a8978d6a8230c5ee"}],"database_specific":{"extracted_events":[{"introduced":"6.6.0"},{"fixed":"6.6.10"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-102599.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}