Is CVE-2026-59724 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-59724?

CVE-2026-59724 has a CVSS v3 severity of HIGH (7.5).

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CVE-2026-59724

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.