Unbound before 1.9.5 allows an integer overflow in the regional allocator via regional_alloc. NOTE: The vendor disputes that this is a vulnerability. Although the code may be vulnerable, a running Unbound installation cannot be remotely or locally exploited
https://security.netapp.com/advisory/ntap-20210507-0007/
https://ostif.org/our-audit-of-unbound-dns-by-x41-d-sec-full-results/
https://lists.debian.org/debian-lts-announce/2021/05/msg00007.html