CVE-2026-59725CWE-404

CVE-2026-59725

High · published July 8, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
49.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00636 · 49.8th percentile
Weakness
CWE-404 · Improper Resource Shutdown or Release
Published
2026-07-08T20:16Z
Affected products (1)
ProductVersionsFixed in
socket/engine.io≥ 4.1.0, < 6.6.76.6.7
References (3)
https://github.com/socketio/socket.io/commit/fc11285e14964c2132d122164bf130c355f60671 · [email protected]https://github.com/socketio/socket.io/releases/tag/[email protected] · [email protected]https://github.com/socketio/socket.io/security/advisories/GHSA-r635-g3xr-vw7x · [email protected]
EPSS history
Timeline
  • 08 JUL 15:37Z
    Socket.IO: Engine.IO Polling Transport Connection Exhaustion
    cvelistv5