CVE-2026-59725

HIGH

Socket.IO: Engine.IO Polling Transport Connection Exhaustion

Title source: cna
STIX 2.1

Description

Socket.IO enables bidirectional and low-latency communication for every platform. From 4.1.0 before 6.6.7, Engine.IO protocol v4 polling transport does not properly close the HTTP response for invalid binary POST requests with Content-Type: application/octet-stream, allowing an unauthenticated attacker to exhaust server-side connections and sockets. This issue is fixed in version 6.6.7.

References (3)

Core 3

Scores

CVSS v3 7.5
EPSS 0.0035
EPSS Percentile 28.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-404
Status published
Products (3)
npm/engine.io 4.1.0 - 6.6.7npm
socket/engine.io 4.1.0 - 6.6.7
socketio/socket.io >= 4.1.0, < 6.6.7
Published Jul 08, 2026
Tracked Since Jul 08, 2026