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.
http://www.openwall.com/lists/oss-security/2018/08/21/6
http://www.securityfocus.com/bid/105177
http://www.securitytracker.com/id/1041543
https://access.redhat.com/errata/RHSA-2019:2079
https://bugzilla.suse.com/show_bug.cgi?id=1102068
https://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=dbf72805fd9d7b1846fe9a11b46f3994bfc27fea
https://lists.debian.org/debian-lts-announce/2018/08/msg00030.html
https://lists.x.org/archives/xorg-announce/2018-August/002916.html
https://security.gentoo.org/glsa/201811-01
Source: MITRE
Published: 2018-08-24
Updated: 2019-08-06
Type: CWE-787
Base Score: 7.5
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 10
Severity: HIGH
Base Score: 9.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 3.9
Severity: CRITICAL