How severe is CVE-2024-38355?

CVE-2024-38355 has a CVSS score of 7.3/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2024-38355?

CVE-2024-38355 affects the following packages: socket.io (npm), socket.io (npm). Ecosystems affected: npm.

How do I fix CVE-2024-38355?

Update socket.io to 2.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-38355 is resolved across your whole dependency graph.

How do I detect CVE-2024-38355 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for socket.io, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2024-38355 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2024-38355 actively exploited in the wild?

No public exploit code has been indexed for CVE-2024-38355 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2024-38355?

CVE-2024-38355 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 57th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2024-38355?

CVE-2024-38355 is classified as Improper Input Validation (CWE-20), CWE-754 (CWE-754). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2024-38355 published, and has it been updated?

CVE-2024-38355 was published on June 19, 2024 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

CVE-2024-38355 — socket.io

HIGHFix: socketio/socket.io@15af22f

CVE-2024-38355 is a high-severity (CVSS 7.3) Improper Input Validation vulnerability in socket.io. A fix is available for socket.io — see the affected versions and patch details below.

Unhandled 'error' event in socket.io

Also known asGHSA-25hc-qcg6-38wj

Published

Jun 19, 2024

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2024-38355.

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs57th percentile — riskier than 57% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

12Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

socket.ionpm

25.1Mdownloads / week

Description

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:

io.on("connection", (socket) => {
  socket.on("error", () => {
    // ...
  });
});

For more information

If you have any questions or comments about this advisory:

Open a discussion here

Thanks a lot to Paul Taylor for the responsible disclosure.

References

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`socket.io`	all versions	2.5.1`npm install socket.io@2.5.1`
📦npm	`socket.io`	≥ 3.0.0&&< 4.6.2	4.6.2`npm install socket.io@4.6.2`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for socket.io, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update socket.io to 2.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-38355 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This flaw occurs because the server fails to handle certain errors properly, leading to a complete server shutdown. Since the attack requires no special privileges or user interaction and can be done remotely, it poses a significant risk to server stability and availability. This vulnerability is rated as IMPORTANT…

Workaround published by Red Hat

It is recommended to update to the latest version to address this vulnerability.

Source: Red Hat security advisory for CVE-2024-38355 (CC BY 4.0)

Frequently Asked Questions

### 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