pupnp is an SDK for development of UPnP device and control point applications. Prior to 22.0.4, parsehostport in upnp/src/genlib/net/uri/uri.c synchronously calls getaddrinfo while parseuri is processing attacker-supplied hostnames from inbound HTTP request targets in upnp/src/genlib/net/http/httpparser.c and GENA SUBSCRIBE CALLBACK headers handled by createurllist in upnp/src/gena/genadevice.c. A remote unauthenticated peer can choose a slow or nonresponsive hostname and block a bounded miniserver worker for the resolver timeout, allowing a small number of requests to exhaust the thread pool and deny UPnP service. This issue is fixed in 22.0.4.