dnsmasq: DHCPv6 CLID buffer overflow in helper process

A heap buffer overflow was discovered in dnsmasq's DHCP script helper process. When processing DHCPv6 client identifiers CLIDs, the helper hex-encodes the raw CLID bytes into a fixed-size buffer without length validation. Since DHCPv6 CLIDs can be up to 65,535 bytes, a crafted DHCPv6 packet can...