PT-2026-56488 · Socket.Io · Socket.Io

Published 2026-07-08 · Updated 2026-07-08 · CVE-2026-59725

NVD

CVSS v3.1

7.5

High

Base vector

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

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.

Fix

Improper Resource Release

Weakness Enumeration

CWE-404

Related Identifiers

CVE-2026-59725

Affected Products

Socket.Io

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-59725 · Security Note
• https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671 · Note
• https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x · Note
• https://github.com/socketio/socket.io/releases/tag/engine.io@6.6.7 · Note