CVE-2022-41940

Uncaught exception in engine.io

Workarounds

There is no known workaround except upgrading to a safe version.

For more information

If you have any questions or comments about this advisory:

• Open an issue in engine.io

Thanks to Jonathan Neve for the responsible disclosure.

A specially crafted HTTP request can trigger an uncaught exception on the Engine.IO server, thus killing the Node.js process.

events.js:292
      throw er; // Unhandled 'error' event
      ^

Error: read ECONNRESET
    at TCP.onStreamRead (internal/stream_base_commons.js:209:20)
Emitted 'error' event on Socket instance at:
    at emitErrorNT (internal/streams/destroy.js:106:8)
    at emitErrorCloseNT (internal/streams/destroy.js:74:3)
    at processTicksAndRejections (internal/process/task_queues.js:80:21) {
  errno: -104,
  code: 'ECONNRESET',
  syscall: 'read'
}

This impacts all the users of the engine.io package, including those who uses depending packages like socket.io.

CVE-2022-41940 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.6.1, 6.2.1); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

A fix has been released today (2022/11/20):

For socket.io users:

1. What is CVE-2022-41940? CVE-2022-41940 is a medium-severity security vulnerability in engine.io (npm), affecting versions < 3.6.1. It is fixed in 3.6.1, 6.2.1.
2. How severe is CVE-2022-41940? CVE-2022-41940 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of engine.io are affected by CVE-2022-41940? engine.io (npm) versions < 3.6.1 is affected.
4. Is there a fix for CVE-2022-41940? Yes. CVE-2022-41940 is fixed in 3.6.1, 6.2.1. Upgrade to this version or later.
5. Is CVE-2022-41940 exploitable, and should I be worried? Whether CVE-2022-41940 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2022-41940 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2022-41940?
   • Upgrade engine.io to 3.6.1 or later
   • Upgrade engine.io to 6.2.1 or later

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