CVE-2026-102600

Socket.IO: Prototype Pollution via Unsafe Client Session Lookup

Published Sep 29, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-wfpm-5gcm-94cg Socket.IO: Prototype Pollution via Unsafe Client Session Lookup
History
Type Values Removed Values Added
First Time appeared Socket
Socket cluster-engine
Socket socket.io
Vendors & Products Socket
Socket cluster-engine
Socket socket.io
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Socket.IO: Prototype Pollution via Unsafe Client Session Lookup
Weaknesses CWE-1321
CWE-20
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 29, 2026, 4:28 PM
Reserved
Sep 29, 2026, 2:18 PM
Status
Awaiting Analysis
Published
Sep 29, 2026, 4:17 PM
Modified
Sep 30, 2026, 7:38 PM