CVE-2026-102600
Socket.IO: Prototype Pollution via Unsafe Client Session Lookup
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
Socket.IO enables bidirectional and low-latency communication for every platform. Prior to 0.1.1, @socket.io/cluster-engine uses inherited object properties when looking up attacker-controlled session IDs in clustered deployments. Special property names such as __proto__ or constructor can resolve through the object prototype chain instead of identifying an actual connected client, causing the Node.js process to crash and resulting in denial of service. Applications that do not use @socket.io/cluster-engine are not affected. This issue is fixed in version 0.1.1.
| CWE | CWE-20 CWE-1321 |
| Vendor | socketio |
| Product | socket.io |
| Published | Sep 29, 2026 |
| Last Updated | Sep 29, 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
< 0.1.1
@socket.io / cluster-engine
< 0.1.1