CVE-2026-59724
Socket.IO: Engine.IO WebTransport SID DoS
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-20 |
| Vendor | socketio |
| Product | socket.io |
| Published | Jul 8, 2026 |
| Last Updated | Jul 8, 2026 |
Stay Ahead of the Next One
Get instant alerts for socketio socket.io
Be the first to know when new high vulnerabilities affecting socketio socket.io are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
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
>= 6.5.0, < 6.6.7