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.
https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2025-01.html