The i386_set_ldt system call in NetBSD 1.5 and earlier, and OpenBSD 2.8 and earlier, when the USER_LDT kernel option is enabled, does not validate a call gate target, which allows local users to gain root privileges by creating a segment call gate in the Local Descriptor Table (LDT) with a target that specifies an arbitrary kernel address.
archives.neohapsis.com/archives/bugtraq/2001-02/0353.html
archives.neohapsis.com/archives/linux/caldera/2001-q4/0014.html
archives.neohapsis.com/archives/netbsd/2001-q1/0093.html
www.kb.cert.org/vuls/id/358960
www.openbsd.org/errata.html#userldt
www.osvdb.org/6141
www.securityfocus.com/bid/2739
exchange.xforce.ibmcloud.com/vulnerabilities/6222