{"cve":"CVE-2026-102599","nvd":{"published":"2026-10-13T19:17:49.037","modified":"2026-10-17T02:17:08.197","status":"Awaiting Analysis","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-248"],"references":["https://github.com/socketio/socket.io/commit/86db1fc3db2cd315a065d64c4e48918ccf9b4729","https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.10","https://github.com/socketio/socket.io/security/advisories/GHSA-2gc4-cqfq-p2gv"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:58:52.678897993+00:00"},"epss":{"cve":"CVE-2026-102599","score":0.00576,"percentile":0.47214,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-2gc4-cqfq-p2gv","url":"https://osv.dev/vulnerability/GHSA-2gc4-cqfq-p2gv","summary":"Socket.IO: Engine.IO Protocol Revision Mismatch DoS","modified":"2026-09-30T00:00:03.845828732Z","packages":[{"ecosystem":"npm","name":"engine.io","purl":"pkg:npm/engine.io","ranges":[">=6.6.0 <6.6.10"],"fixed":["6.6.10"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}