CVE-2023-31125Network attack vector

Process crash via falsy transport error code

Published May 8, 2023 · Updated Feb 13, 2025

Uncaught exception in Socket.IO Engine.IO 5.1.0 through 6.4.1 allows remote authenticated users to crash the Node.js process. A transport value of proto produces error code 0, but the server callback treats that falsy code as success and dereferences an undefined transport. A reachable Engine.IO endpoint and client-level access are required; a WebSocket upgrade terminates the hosting process without changing or exposing data.

CVSS severity6.5
Medium
EPSS probability1.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncaught exception in Socket.IO Engine.IO 5.1.0 through 6.4.1 allows remote authenticated users to crash the Node.js process. A transport value of proto produces error code 0, but the server callback treats that falsy code as success and dereferences an undefined transport. A reachable Engine.IO endpoint and client-level access are required; a WebSocket upgrade terminates the hosting process without changing or exposing data.

The record

CVE
CVE-2023-31125
Published
May 8, 2023
Updated
Feb 13, 2025
Vendor
Socket.IO
Product
Engine.IO
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 8, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 5.1.0, < 6.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Socket.IO · Engine.IOversion=>= 5.1.0, < 6.4.2

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-248Uncaught Exception
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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