{"id":"CVE-2026-102599","published":"2026-10-13T19:17:49.037","lastModified":"2026-10-17T02:17:08.197","description":"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.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-248"],"vendors":[],"products":[],"references":[{"url":"https://github.com/socketio/socket.io/commit/86db1fc3db2cd315a065d64c4e48918ccf9b4729","tags":[]},{"url":"https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.10","tags":[]},{"url":"https://github.com/socketio/socket.io/security/advisories/GHSA-2gc4-cqfq-p2gv","tags":[]}],"exploitRefs":[{"url":"https://github.com/socketio/socket.io/commit/86db1fc3db2cd315a065d64c4e48918ccf9b4729","tags":[]},{"url":"https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.10","tags":[]},{"url":"https://github.com/socketio/socket.io/security/advisories/GHSA-2gc4-cqfq-p2gv","tags":[]}],"hasPoc":true,"ai":null}