Unhandled 'error' event in socket.io

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Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. A specially crafted Socket.IO packet can trigger an uncaught exception on the Socket.IO server, thus killing the Node.js process. This issue is fixed by commit `15af22fc22` which has been included in `[email protected]` (released in May 2023). The fix was backported in the 2.x branch as well with commit `d30630ba10`. Users are advised to upgrade. Users unable to upgrade may attach a listener for the "error" event to catch these errors.

Source published

19 Jun 2024 19:48:50 UTC

Source modified

3 Sep 2024 20:35:40 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVE Program Terms of Use

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CVSS 3.1 · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. A specially crafted Socket.IO packet can trigger an uncaught exception on the Socket.IO server, thus killing the Node.js process. This issue is fixed by commit `15af22fc22` which has been included in `[email protected]` (released in May 2023). The fix was backported in the 2.x branch as well with commit `d30630ba10`. Users are advised to upgrade. Users unable to upgrade may attach a listener for the "error" event to catch these errors.

Source published

Jun 19, 2024, 7:48:50 PM (timezone not stated)

Source modified

Sep 3, 2024, 8:35:40 PM (timezone not stated)

Saved here

11 Nov 2026 00:42:47 UTC

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ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. A specially crafted Socket.IO packet can trigger an uncaught exception on the Socket.IO server, thus killing the Node.js process. This issue is fixed by commit `15af22fc22` which has been included in `[email protected]` (released in May 2023). The fix was backported in the 2.x branch as well with commit `d30630ba10`. Users are advised to upgrade. Users unable to upgrade may attach a listener for the "error" event to catch these errors.

Source published

19 Jun 2024 20:15:11 UTC

Source modified

17 Jun 2026 07:39:58 UTC

Saved here

25 Oct 2026 00:17:15 UTC

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CVSS 3.1 · [email protected] · Secondary · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

### Impact A specially crafted Socket.IO packet can trigger an uncaught exception on the Socket.IO server, thus killing the Node.js process. ``` node:events:502 throw err; // Unhandled 'error' event ^ Error [ERR_UNHANDLED_ERROR]: Unhandled error. (undefined) at new NodeError (node:internal/errors:405:5) at Socket.emit (node:events:500:17) at /myapp/node_modules/socket.io/lib/socket.js:531:14 at process.processTicksAndRejections (node:internal/process/task_queues:77:11) { code: 'ERR_UNHANDLED_ERROR', context: undefined } ``` ### Affected versions | Version range | Needs minor update? | |------------------|------------------------------------------------| | `4.6.2...latest` | Nothing to do | | `3.0.0...4.6.1` | Please upgrade to `[email protected]` (at least) | | `2.3.0...2.5.0` | Please upgrade to `[email protected]` | ### Patches This issue is fixed by https://github.com/socketio/socket.io/commit/15af22fc22bc6030fcead322c106f07640336115, included in `[email protected]` (released in May 2023). The fix was backported in the 2.x branch today: https://github.com/socketio/socket.io/commit/d30630ba10562bf987f4d2b42440fc41a828119c ### Workarounds As a workaround for the affected versions of the `socket.io` package, you can attach a listener for the "error" event: ```js io.on("connection", (socket) => { socket.on("error", () => { // ... }); }); ``` ### For more information If you have any questions or comments about this advisory: - Open a discussion [here](https://github.com/socketio/socket.io/discussions) Thanks a lot to [Paul Taylor](https://github.com/Y0ursTruly) for the responsible disclosure. ### References - https://github.com/socketio/socket.io/commit/15af22fc22bc6030fcead322c106f07640336115 - https://github.com/socketio/socket.io/commit/d30630ba10562bf987f4d2b42440fc41a828119c

Source published

19 Jun 2024 15:04:41 UTC

Source modified

24 Sep 2026 15:00:04 UTC

Saved here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

Publisher rating · MODERATE