PYSEC-2026-3439 zeroconf has unbounded DNS record cache that allows LAN-local memory exhaustion via multicast flood

Impact DNSCache.asyncadd inserted every response record into cache, expirations, expireheap, and servicecache with no cap on entry count. The only pre-existing protection was a PTR TTL floor DNSPTRMINTTL = 1125 s, RFC 6762 §10, which actually prolonged attacker-injected records, and a periodic...