CVE-2026-109924: undici vulnerable to Denial of Service via unbounded memory in the EventSource parser

undici’s EventSource client can be driven to exhaust process memory by a malicious or compromised Server-Sent Events peer. By sending millions of tiny completed data: fields with no blank event separator, or a single unfinished line split across many chunks, the parser retains a growing amount of per-field and per-chunk state. The byte-based maxEventSize and maxResponseSize limits do not bound that retained state, and maxResponseSize is enforced on the compressed body before decompression, so a small compressed response can expand into enough retained memory to terminate the process. The application only needs to maintain an EventSource connection to an untrusted peer, which controls only the response. Availability is the only impact.