Implementations of UDP application protocol are vulnerable to network loops. An unauthenticated attacker can use maliciously-crafted packets against a vulnerable implementation that can lead to Denial of Service (DOS) and/or abuse of resources.

dproxy-nexgen (aka dproxy nexgen) forwards and caches DNS queries with the CD (aka checking disabled) bit set to 1. This leads to disabling of DNSSEC protection provided by upstream resolvers.

Misinterpretation of special domain name characters in dproxy-nexgen (aka dproxy nexgen) leads to cache poisoning because domain names and their associated IP addresses are cached in their misinterpreted form.

dproxy-nexgen (aka dproxy nexgen) uses a static UDP source port (selected randomly only at boot time) in upstream queries sent to DNS resolvers. This allows DNS cache poisoning because there is not enough entropy to prevent traffic injection attacks.

dproxy-nexgen (aka dproxy nexgen) re-uses the DNS transaction id (TXID) value from client queries, which allows attackers (able to send queries to the resolver) to conduct DNS cache-poisoning attacks because the TXID value is known to the attacker.