slaacd in OpenBSD 6.9 and 7.0 before 2022-03-22 has an integer signedness error and resultant heap-based buffer overflow triggerable by a crafted IPv6 router advertisement. NOTE: privilege separation and pledge can prevent exploitation.
https://security.netapp.com/advisory/ntap-20220506-0005/
https://ftp.openbsd.org/pub/OpenBSD/patches/7.0/common/017_slaacd.patch.sig
https://ftp.openbsd.org/pub/OpenBSD/patches/6.9/common/033_slaacd.patch.sig
https://blog.quarkslab.com/heap-overflow-in-openbsds-slaacd-via-router-advertisement.html