An issue was discovered in libX11 through 1.6.5. The function XListExtensions in ListExt.c interprets a variable as signed instead of unsigned, resulting in an out-of-bounds write (of up to 128 bytes), leading to DoS or remote code execution.
www.openwall.com/lists/oss-security/2018/08/21/6
www.securityfocus.com/bid/105177
www.securitytracker.com/id/1041543
access.redhat.com/errata/RHSA-2019:2079
bugzilla.suse.com/show_bug.cgi?id=1102068
cgit.freedesktop.org/xorg/lib/libX11/commit/?id=dbf72805fd9d7b1846fe9a11b46f3994bfc27fea
lists.debian.org/debian-lts-announce/2018/08/msg00030.html
lists.x.org/archives/xorg-announce/2018-August/002916.html
security.gentoo.org/glsa/201811-01
usn.ubuntu.com/3758-1/
usn.ubuntu.com/3758-2/