CVE-2026-33151 PUBLISHED

socket.io allows an unbounded number of binary attachments

Assigner: GitHub_M
Reserved: 17.03.2026 Published: 20.03.2026 Updated: 20.03.2026

Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. Prior to versions 3.3.5, 3.4.4, and 4.2.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This issue has been patched in versions 3.3.5, 3.4.4, and 4.2.6.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS Score: 8.7

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	socketio
Product	socket.io
Versions	Version < 3.3.5 is affected Version >= 3.4.0, < 3.4.4 is affected Version >= 4.0.0, < 4.2.6 is affected

References

Problem Types

CWE-20: Improper Input Validation CWE
CWE-754: Improper Check for Unusual or Exceptional Conditions CWE