{"id":"CVE-2023-31125","aliases":["GHSA-q9mw-68c2-j6m5"],"url":"https://o3.security/vulnerability/CVE-2023-31125","summary":"Uncaught exception in engine.io","details":"### Impact\n\nA specially crafted HTTP request can trigger an uncaught exception on the Engine.IO server, thus killing the Node.js process.\n\n```\nTypeError: Cannot read properties of undefined (reading 'handlesUpgrades')\n    at Server.onWebSocket (build/server.js:515:67)\n```\n\nThis impacts all the users of the [`engine.io`](https://www.npmjs.com/package/engine.io) package, including those who uses depending packages like [`socket.io`](https://www.npmjs.com/package/socket.io).\n\n### Patches\n\nA fix has been released today (2023/05/02): [6.4.2](https://github.com/socketio/engine.io/releases/tag/6.4.2)\n\nThis bug was introduced in version 5.1.0 and included in version 4.1.0 of the `socket.io` parent package. Older versions are not impacted.\n\nFor `socket.io` users:\n\n| Version range               | `engine.io` version | Needs minor update?                                                                                    |\n|-----------------------------|---------------------|--------------------------------------------------------------------------------------------------------|\n| `socket.io@4.6.x`           | `~6.4.0`            | `npm audit fix` should be sufficient                                                                   |\n| `socket.io@4.5.x`           | `~6.2.0`            | Please upgrade to `socket.io@4.6.x`                                                                    |\n| `socket.io@4.4.x`           | `~6.1.0`            | Please upgrade to `socket.io@4.6.x`                                                                    |\n| `socket.io@4.3.x`           | `~6.0.0`            | Please upgrade to `socket.io@4.6.x`                                                                    |\n| `socket.io@4.2.x`           | `~5.2.0`            | Please upgrade to `socket.io@4.6.x`                                                                    |\n| `socket.io@4.1.x`           | `~5.1.1`            | Please upgrade to `socket.io@4.6.x`                                                                    |\n| `socket.io@4.0.x`           | `~5.0.0`            | Not impacted |\n| `socket.io@3.1.x`           | `~4.1.0`            | Not impacted |\n| `socket.io@3.0.x`           | `~4.0.0`            | Not impacted |\n| `socket.io@2.5.0`           | `~3.6.0`            | Not impacted |\n| `socket.io@2.4.x` and below | `~3.5.0`            | Not impacted |\n\n### Workarounds\n\nThere is no known workaround except upgrading to a safe version.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n* Open an issue in [`engine.io`](https://github.com/socketio/engine.io)\n\nThanks to Thomas Rinsma from Codean for the responsible disclosure.","published":"2023-05-08T20:21:01.341Z","modified":"2026-08-12T03:51:16.745110399Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.01327,"percentile":0.69613,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"engine.io","fixedVersion":"6.4.2"}],"fix":{"url":"https://github.com/socketio/engine.io/commit/fc480b4f305e16fe5972cf337d055e598372dc44","label":"socketio/engine.io@fc480b4"},"references":[{"type":"WEB","url":"https://github.com/socketio/engine.io/releases/tag/6.4.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/31xxx/CVE-2023-31125.json"},{"type":"ADVISORY","url":"https://github.com/socketio/engine.io/security/advisories/GHSA-q9mw-68c2-j6m5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-31125"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20230622-0002/"},{"type":"FIX","url":"https://github.com/socketio/engine.io/commit/fc480b4f305e16fe5972cf337d055e598372dc44"},{"type":"PACKAGE","url":"https://github.com/socketio/engine.io"},{"type":"WEB","url":"https://security.netapp.com/advisory/ntap-20230622-0002"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:16.745110399Z"}}