Socket.IO enables bidirectional and low-latency communication for every platform. From 6.5.0 before 6.6.7, Engine.IO servers with WebTransport enabled can resolve a crafted session ID such as __proto__ through an inherited property of the clients object during WebTransport upgrade handling, causing a TypeError and denial of service. This issue is fixed in version 6.6.7.

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Fixes

Solution

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Workaround

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History

Fri, 10 Jul 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-843
References
Metrics threat_severity

None

threat_severity

Important


Fri, 10 Jul 2026 09:30:00 +0000

Type Values Removed Values Added
First Time appeared Socket
Socket socket.io
Vendors & Products Socket
Socket socket.io

Wed, 08 Jul 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Wed, 08 Jul 2026 15:45:00 +0000

Type Values Removed Values Added
Description Socket.IO enables bidirectional and low-latency communication for every platform. From 6.5.0 before 6.6.7, Engine.IO servers with WebTransport enabled can resolve a crafted session ID such as __proto__ through an inherited property of the clients object during WebTransport upgrade handling, causing a TypeError and denial of service. This issue is fixed in version 6.6.7.
Title Socket.IO: Engine.IO WebTransport SID DoS
Weaknesses 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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-08T19:41:18.905Z

Reserved: 2026-07-06T15:34:16.916Z

Link: CVE-2026-59724

cve-icon Vulnrichment

Updated: 2026-07-08T17:58:47.574Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-08T15:35:39Z

Links: CVE-2026-59724 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-26T17:45:17Z

Weaknesses