CVE-2026-102599

A flaw was found in engine.io. A remote attacker can cause a Denial of Service DoS by establishing a valid session and sending a transport upgrade request with a mismatched or omitted protocol revision parameter. This discrepancy causes the server to attach incompatible communication handlers,...

CVE-2026-102599

Socket.IO enables bidirectional and low-latency communication for every platform. From Engine.IO 6.6.0 until 6.6.10, a transport upgrade can independently derive an Engine.IO protocol revision from the upgrade request instead of enforcing the revision stored on the existing session. A malicious...

CVE-2026-102599 Socket.IO: Engine.IO Protocol Revision Mismatch DoS

Socket.IO enables bidirectional and low-latency communication for every platform. From Engine.IO 6.6.0 until 6.6.10, a transport upgrade can independently derive an Engine.IO protocol revision from the upgrade request instead of enforcing the revision stored on the existing session. A malicious...

NPM: Socket.IO: Engine.IO Protocol Revision Mismatch DoS

NPM: Socket.IO: Engine.IO Protocol Revision Mismatch DoS vulnerability discovered by ? in WordPress Npm engine.io versions = 6.6.0, 6.6.10...

GHSA-2GC4-CQFQ-P2GV Socket.IO: Engine.IO Protocol Revision Mismatch DoS

Impact A denial-of-service vulnerability exists in Engine.IO / Socket.IO servers that allow transport upgrades. The Engine.IO protocol revision is negotiated during the initial handshake and stored on the session, but a newly-created transport, including a WebSocket upgrade transport, could...

Socket.IO: Engine.IO Protocol Revision Mismatch DoS

Impact A denial-of-service vulnerability exists in Engine.IO / Socket.IO servers that allow transport upgrades. The Engine.IO protocol revision is negotiated during the initial handshake and stored on the session, but a newly-created transport, including a WebSocket upgrade transport, could...

PT-2026-102976

Name of the Vulnerable Software and Affected Versions Engine.IO versions 6.6.0 through 6.6.9 Description A denial-of-service issue exists in servers that allow transport upgrades. During a transport upgrade, the server may independently derive an Engine.IO protocol revision from the upgrade reque...