In helper.c:265, the DHCPv6 CLID is hex-encoded via sprintf("%.2x") into daemon->packet (5,131 bytes) with no length cap on the CLID. DHCPv6 CLIDs can be up to 65,535 bytes (131,070 hex characters). The helper process retains root privileges. log6packet() already caps CLID to 100 bytes for logging, but the helper code path was missed. Fix: add && i < 100 bound to the encoding loop, matching the logging cap.