xlock in OpenBSD 6.6 allows local users to gain the privileges of the auth group by providing a LIBGL_DRIVERS_PATH environment variable, because xenocara/lib/mesa/src/loader/loader.c mishandles dlopen.
https://www.openbsd.org/errata66.html
http://www.openwall.com/lists/oss-security/2019/12/04/6