AIKIDO-2026-145478

TL;DR

undici's WebSocket client enforces the maxPayloadSize limit on the cumulative byte size of a fragmented message but never limits the number of fragments. A malicious or compromised WebSocket server can stream a very large number of small or empty continuation frames that each pass per-frame and cumulative-size checks while collectively driving unbounded memory growth in the client. An application that connects its WebSocket or WebSocketStream client to an attacker-controlled endpoint can be driven to memory exhaustion and denial of service. The fix adds a limit on the number of accepted fragments so a message cannot grow without bound.