Crafted delegations or IP fragments can poison cached delegations in Recursor.

Crafted zones can lead to increased resource usage and crafted CNAME chains can lead to cache poisoning in Recursor.

Crafted delegations or IP fragments can poison cached delegations in Recursor.

Crafted zones can lead to increased incoming network traffic.

An attacker can trigger the removal of cached records by sending a NOTIFY query over TCP.

An attacker can trigger an assertion failure by requesting crafted DNS records, waiting for them to be inserted into the records cache, then send a query with qtype set to ANY.

An attacker spoofing answers to ECS enabled requests sent out by the Recursor has a chance of success higher than non-ECS enabled queries. The updated version include various mitigations against spoofing attempts of ECS enabled queries by chaining ECS enabled requests and enforcing stricter validation of the received answers. The most strict mitigation done when the new setting outgoing.edns_subnet_harden (old style name edns-subnet-harden) is enabled.

An attacker can publish a zone containing specific Resource Record Sets. Processing and caching results for these sets can lead to an illegal memory accesses and crash of the Recursor, causing a denial of service. The remedy is: upgrade to the patched 5.2.1 version. We would like to thank Volodymyr Ilyin for bringing this issue to our attention.

An attacker can publish a zone containing specific Resource Record Sets. Repeatedly processing and caching results for these sets can lead to a denial of service.

A crafted response from an upstream server the recursor has been configured to forward-recurse to can cause a Denial of Service in the Recursor. The default configuration of the Recursor does not use recursive forwarding and is not affected.