CVE-2022-21676Network attack vector

Process crash via mishandled WebSocket handshake errors

Published Jan 12, 2022 · Updated Apr 23, 2025

Uncaught exceptions in affected Engine.IO 4.x through 6.x releases allow remote attackers to crash the Node.js server via crafted HTTP requests. During WebSocket handshakes, server.js removes its upgrade-error listener before calling handshake, so invalid frame data raises an unhandled RangeError. No authentication or user interaction is required, and each successful request terminates the hosting Node.js process rather than affecting confidentiality or integrity.

CVSS severity7.5
High
EPSS probability2.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncaught exceptions in affected Engine.IO 4.x through 6.x releases allow remote attackers to crash the Node.js server via crafted HTTP requests. During WebSocket handshakes, server.js removes its upgrade-error listener before calling handshake, so invalid frame data raises an unhandled RangeError. No authentication or user interaction is required, and each successful request terminates the hosting Node.js process rather than affecting confidentiality or integrity.

The record

CVE
CVE-2022-21676
Published
Jan 12, 2022
Updated
Apr 23, 2025
Vendor
Socket.IO
Product
Engine.IO
Classifications
CWE-248, CWE-755, CWE-754, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 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=>= 4.0.0, < 4.1.2
  2. Affected versionversion=>= 5.0.0, < 5.2.1
  3. Affected versionversion=>= 6.0.0, < 6.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Socket.IO · Engine.IOversion=>= 4.0.0, < 4.1.2; version=>= 5.0.0, < 5.2.1; version=>= 6.0.0, < 6.1.1

Published CVSS scores

5.0NISTAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-248Uncaught Exception
CWE-755Improper Handling of Exceptional Conditions
CWE-754Improper Check for Unusual or Exceptional Conditions
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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