Errata patches for unwind have been released for OpenBSD 6.7 and 6.8. unwind fails to process large DNS replies.
Binary updates for the amd64, i386, and arm64 platforms are available via the syspatch utility. Source code patches can be found on the respective errata page: https://www.openbsd.org/errata67.html https://www.openbsd.org/errata68.html