CVE-2026-33151CWE-20CWE-754

socket.io allows an unbounded number of binary attachments

High · published March 20, 2026

CVSS v4.0
8.7
EPSS
1%
Percentile
50.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.7 · HIGH
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
EPSS
0.00654 · 50.7th percentile
Weaknesses
CWE-20 · Improper Input Validation; CWE-754 · Improper Check for Unusual or Exceptional Conditions
Published
2026-03-20T20:13Z
EPSS history
Timeline
  • 20 MAR 20:13Z
    socket.io allows an unbounded number of binary attachments
    cvelistv5