{"schema":"threatline.record/2","record":{"id":"CVE-2026-102600","aliases":["GHSA-wfpm-5gcm-94cg"],"summary":"Socket.IO: Prototype Pollution via Unsafe Client Session Lookup","details":"### Impact\n\nThis is a **prototype pollution / improper client lookup** vulnerability in `@socket.io/cluster-engine`.\n\nServers using `@socket.io/cluster-engine` may be impacted when attacker-controlled session IDs are processed in clustered deployments. A malicious client could use special property names such as `__proto__`, `constructor`, or other inherited object keys as a session identifier, causing the server to read properties from the object prototype chain instead of only real connected clients.\n\nThe impact is **denial of service** through process crash.\n\nApplications not using `@socket.io/cluster-engine` are not affected by this specific issue.\n\nAffected versions:\n\n*  `@socket.io/cluster-engine@0.1.0`\n\n### Patches\n\nThe issue was fixed in:\n\n*  `@socket.io/cluster-engine@0.1.1`\n\n### Workarounds\n\nIf upgrading immediately is not possible, users can reduce exposure by:\n\n- Rejecting or sanitizing suspicious session IDs before they reach the cluster engine.\n- Running the cluster engine behind trusted infrastructure that prevents arbitrary clients from crafting raw Engine.IO session-related requests.\n\nThese workarounds are defense-in-depth only. Upgrading to a patched version is recommended.","categories":["Libraries & packages"],"product":"@socket.io/cluster-engine","vendor":"socketio","ecosystem":"npm","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-wfpm-5gcm-94cg","source_modified_at":"2026-10-05T23:44:22Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"@socket.io/cluster-engine"},"range":"< 0.1.1"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-102600","source_modified_at":"2026-09-29T16:28:28.476Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"socket.io","vendor":"socketio","versions":[{"version":"< 0.1.1","status":"affected"}],"defaultStatus":null},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-102600","source_modified_at":"2026-09-29T16:28:28.476Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"cluster-engine","vendor":"@socket.io","versions":[{"version":"< 0.1.1","status":"affected"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-wfpm-5gcm-94cg","source_modified_at":"2026-10-06T00:00:08.444830774Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"@socket.io/cluster-engine","purl":"pkg:npm/%40socket.io/cluster-engine"},"ranges":[{"events":[{"introduced":"0"},{"fixed":"0.1.1"}],"type":"SEMVER"}],"versions":[]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-wfpm-5gcm-94cg","source_modified_at":"2026-10-05T23:44:22Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"@socket.io/cluster-engine"},"version":"0.1.1"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-wfpm-5gcm-94cg","source_modified_at":"2026-10-06T00:00:08.444830774Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"@socket.io/cluster-engine","purl":"pkg:npm/%40socket.io/cluster-engine"},"version":"0.1.1"}],"cvss":7.5,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00366,"percentile":0.29299,"score_date":"2026-10-23"},"published_at":"2026-09-29T15:23:15.857Z","modified_at":"2026-10-06T00:00:08.444830774Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-wfpm-5gcm-94cg","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-05T23:44:22Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-102600","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-09-29T16:28:28.476Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-wfpm-5gcm-94cg","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-06T00:00:08.444830774Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-102600","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/socketio/socket.io/security/advisories/GHSA-wfpm-5gcm-94cg","tags":["x_refsource_CONFIRM"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-102600","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://github.com/socketio/socket.io/commit/830e3642ebb8dc3784eb749b0a004fe2b932b429","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/socketio/socket.io/releases/tag/@socket.io/cluster-engine@0.1.1","tags":["x_refsource_MISC"]},{"url":"https://github.com/advisories/GHSA-wfpm-5gcm-94cg","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-09-29T16:27:29.573677Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-06T00:00:08.444830774Z","content_hash":"702b321f111712f17356af81b54877b2bc36f3a61d7d2637a8b7983eebb9be2d"}}