In OpenBSD 6.6, local users can use the su -L option to achieve any login class (often excluding root) because there is a logic error in the main function in su/su.c.
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
github.com/openbsd/src/blob/2dfc98f42e117c7605b52b5020b630d98601dc22/usr.bin/su/su.c#L210-L211
seclists.org/bugtraq/2019/Dec/8
www.openbsd.org/errata66.html
www.openwall.com/lists/oss-security/2019/12/04/5