CVE-2026-59725
Socket.IO: Engine.IO Polling Transport Connection Exhaustion
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-404 |
| Vendor | socketio |
| Product | socket.io |
| Published | Jul 8, 2026 |
| Last Updated | Jul 8, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
socketio / socket.io
>= 4.1.0, < 6.6.7