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Fencer Vulns
critical 9.8

CVE-2018-14599 json

An issue was discovered in libX11 through 1.6.5.

published 2018-08-24 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-6506

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.2%
EPSS 4.2% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

An issue was discovered in libX11 through 1.6.5. The function XListExtensions in ListExt.c is vulnerable to an off-by-one error caused by malicious server responses, leading to DoS or possibly unspecified other impact.

Patch / fix

  • libx11 Debian 14, Debian 13, Debian 12 2:1.6.6-1

debian advisories DEBIAN-CVE-2018-14599

  • libx11 Ubuntu 14.04 LTS 2:1.6.2-1ubuntu2.1
  • libx11 Ubuntu 16.04 LTS 2:1.6.3-1ubuntu2.1
  • libx11 Ubuntu 18.04 LTS 2:1.6.4-3ubuntu0.1

ubuntu advisories UBUNTU-CVE-2018-14599

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • gdm RHEL 7 1:3.28.2-16.el7
  • libX11 RHEL 7 1.6.7-2.el7
  • mesa-libGLw RHEL 7 8.0.0-5.el7
  • libxkbcommon RHEL 7 0.7.1-3.el7
  • libX11-common RHEL 7 1.6.7-2.el7
  • xorg-x11-server RHEL 7 1.20.4-7.el7
  • libxkbcommon-x11 RHEL 7 0.7.1-3.el7
  • xorg-x11-drv-ati RHEL 7 19.0.1-2.el7

red hat advisories RHSA-2019:2079

  • libX11 SLES for SAP 12 SP3, SLES 12 SP3, SLED 12 SP3 +1 more 1.6.2-12.5.1
  • libxcb SLES for SAP 12 SP3, SLES 12 SP3, SLED 12 SP3 +1 more 1.10-4.3.1
  • libX11 SLE Module for Basesystem 15 1.6.5-3.3.1
  • xorg-x11-libX11 SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +3 more 7.4-5.11.72.9.1

suse advisories SUSE-SU-2018:3102-1SUSE-SU-2018:2955-1SUSE-SU-2018:2934-1

  • libX11 openSUSE Tumbleweed 1.7.2-1.2

opensuse advisories openSUSE-SU-2024:10918-1

  • libx11 Alpine 3.24, Alpine 3.23, Alpine 3.22 +17 more 1.6.6-r0

alpine advisories ALPINE-CVE-2018-14599

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-14599 updated cvss 8.1

libX11: Off-by-one error in XListExtensions in ListExt.c

  • Red Hat Enterprise Linux 6 libX11, libX11-common
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux Client (v. 7) gdm 3.28.2-16.el7, libX11 1.6.7-2.el7, libxkbcommon 0.7.1-3.el7, libX11-common 1.6.7-2.el7, libxkbcommon-x11 0.7.1-3.el7, xorg-x11-server 1.20.4-7.el7, +6 more Red Hat Enterprise Linux Client Optional (v. 7) xorg-x11-server-Xdmx 1.20.4-7.el7, xorg-x11-server-Xvfb 1.20.4-7.el7, xorg-x11-server-Xnest 1.20.4-7.el7, xorg-x11-server-source 1.20.4-7.el7, xorg-x11-server-Xwayland 1.20.4-7.el7 Red Hat Enterprise Linux ComputeNode (v. 7) libX11 1.6.7-2.el7, libxkbcommon 0.7.1-3.el7, libX11-common 1.6.7-2.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) gdm 3.28.2-16.el7, libxkbcommon-x11 0.7.1-3.el7, xorg-x11-server 1.20.4-7.el7, xorg-x11-drv-wacom 0.36.1-3.el7, xorg-x11-server-Xdmx 1.20.4-7.el7, xorg-x11-server-Xorg 1.20.4-7.el7, +6 more Red Hat Enterprise Linux Server (v. 7) gdm 3.28.2-16.el7, libX11 1.6.7-2.el7, mesa-libGLw 8.0.0-5.el7, libxkbcommon 0.7.1-3.el7, libX11-common 1.6.7-2.el7, libxkbcommon-x11 0.7.1-3.el7, +7 more Red Hat Enterprise Linux Server Optional (v. 7) xorg-x11-server-Xdmx 1.20.4-7.el7, xorg-x11-server-Xvfb 1.20.4-7.el7, xorg-x11-server-Xnest 1.20.4-7.el7, xorg-x11-server-source 1.20.4-7.el7, xorg-x11-server-Xwayland 1.20.4-7.el7
    +2 more products
    Red Hat Enterprise Linux Workstation (v. 7) gdm 3.28.2-16.el7, libX11 1.6.7-2.el7, mesa-libGLw 8.0.0-5.el7, libxkbcommon 0.7.1-3.el7, libX11-common 1.6.7-2.el7, libxkbcommon-x11 0.7.1-3.el7, +7 more Red Hat Enterprise Linux Workstation Optional (v. 7) xorg-x11-server-Xdmx 1.20.4-7.el7, xorg-x11-server-Xvfb 1.20.4-7.el7, xorg-x11-server-Xnest 1.20.4-7.el7, xorg-x11-server-source 1.20.4-7.el7, xorg-x11-server-Xwayland 1.20.4-7.el7
    fixed: vendor fix RHSA-2019:2079
  • Red Hat Enterprise Linux 5 libX11 Red Hat Enterprise Linux 8 libX11, libX11-xcb, libX11-common
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

4.21% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.