An issue was discovered in XListExtensions in ListExt.c in libX11 through 1.6.5. A malicious server can send a reply in which the first string overflows, causing a variable to be set to NULL that will be freed later on, leading to DoS (segmentation fault).
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=1102073
https://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=e83722768fd5c467ef61fa159e8c6278770b45c2
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-20
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH