The process_envvars function in elf/rtld.c in the GNU C Library (aka glibc or libc6) before 2.23 allows local users to bypass a pointer-guarding protection mechanism via a zero value of the LD_POINTER_GUARD environment variable.
hmarco.org/bugs/glibc_ptr_mangle_weakness.html
lists.opensuse.org/opensuse-security-announce/2016-02/msg00036.html
lists.opensuse.org/opensuse-security-announce/2016-02/msg00037.html
lists.opensuse.org/opensuse-security-announce/2016-02/msg00038.html
lists.opensuse.org/opensuse-security-announce/2016-02/msg00039.html
www.debian.org/security/2016/dsa-3480
www.openwall.com/lists/oss-security/2016/01/20/1
www.securityfocus.com/bid/81469
www.securitytracker.com/id/1034811
www.ubuntu.com/usn/USN-2985-1
www.ubuntu.com/usn/USN-2985-2
access.redhat.com/errata/RHSA-2017:1916
lists.fedoraproject.org/pipermail/package-announce/2016-February/177404.html
security.gentoo.org/glsa/201702-11
sourceware.org/bugzilla/show_bug.cgi?id=18928