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.
packetstormsecurity.com/files/155572/Qualys-Security-Advisory-OpenBSD-Authentication-Bypass-Privilege-Escalation.html
seclists.org/fulldisclosure/2019/Dec/14
www.openwall.com/lists/oss-security/2019/12/04/5
www.openwall.com/lists/oss-security/2019/12/04/6
seclists.org/bugtraq/2019/Dec/8
www.openbsd.org/errata66.html
www.openwall.com/lists/oss-security/2019/12/04/5