Errata patches for freetype have been released for OpenBSD 6.1 and 6.0. Heap-based buffer overflows can result in out-of-bounds writes.
Binary updates for the amd64 and i386 platforms are available via the syspatch utility. Source code patches can be found on the respective errata pages: https://www.openbsd.org/errata60.html https://www.openbsd.org/errata61.html If you did not install the xbase set, this issue does not affect you.