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Fencer Vulns
high 7.8

CVE-2020-14363 json

An integer overflow vulnerability leading to a double-free was found in libX11

published 2020-09-11 6 y ago modified 2026-07-25 3 mo ago also EUVD-2020-6506 , GHSA-qmwg-hw9q-xg39 , JLSEC-2026-470

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

An integer overflow vulnerability leading to a double-free was found in libX11. This flaw allows a local privileged attacker to cause an application compiled with libX11 to crash, or in some cases, result in arbitrary code execution. The highest threat from this flaw is to confidentiality, integrity as well as system availability.

Patch / fix

  • julia Xorg_libX11_jll 1.8.6+0
  • x.org libx11 1.6.12
  • libx11 Debian 14, Debian 13, Debian 12 2:1.6.12-1

debian advisories DEBIAN-CVE-2020-14363

  • libx11 Ubuntu 16.04 LTS 2:1.6.3-1ubuntu2.2
  • libx11 Ubuntu 18.04 LTS 2:1.6.4-3ubuntu0.3
  • libx11 Ubuntu 20.04 LTS 2:1.6.9-2ubuntu1.1
  • libx11 Ubuntu Pro 14.04 LTS 2:1.6.2-1ubuntu2.1+esm1

ubuntu advisories UBUNTU-CVE-2020-14363

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

  • mesa RHEL 8 20.3.3-2.el8
  • libdrm RHEL 8 2.4.103-1.el8
  • libX11 RHEL 8 1.6.8-4.el8
  • libglvnd RHEL 8 1:1.3.2-1.el8
  • libinput RHEL 8 1.16.3-1.el8
  • libwacom RHEL 8 1.6-2.el8
  • libX11-xcb RHEL 8 1.6.8-4.el8
  • mesa-libGL RHEL 8 20.3.3-2.el8

red hat advisories RHSA-2021:1804RHSA-2020:4946RHSA-2020:4908

  • libX11 SLES 12 SP5, SLES 12 SP3-BCL, SLES 12 SP2-BCL +15 more 1.6.2-12.15.1
  • libX11 SLE Module for Basesystem 15 SP2, SLE Module for Basesystem 15 SP1, SLE High Performance Computing 15-ESPOS +3 more 1.6.5-3.12.1

suse advisories SUSE-SU-2020:2475-2SUSE-SU-2020:2474-2SUSE-SU-2020:2475-1SUSE-SU-2020:2474-1

  • libX11 openSUSE Tumbleweed 1.7.2-1.2
  • libX11 openSUSE Leap 15.2 1.6.5-lp152.5.9.1
  • libX11 openSUSE Leap 15.1 1.6.5-lp151.4.9.1

opensuse advisories openSUSE-SU-2024:10918-1openSUSE-SU-2020:1370-1openSUSE-SU-2020:1368-1

  • libglvnd AlmaLinux 8 1:1.3.2-1.el8
  • libglvnd-egl AlmaLinux 8 1:1.3.2-1.el8
  • libglvnd-glx AlmaLinux 8 1:1.3.2-1.el8
  • libglvnd-gles AlmaLinux 8 1:1.3.2-1.el8
  • libglvnd-opengl AlmaLinux 8 1:1.3.2-1.el8
  • xorg-x11-drivers AlmaLinux 8 7.7-30.el8
  • xorg-x11-server-source AlmaLinux 8 1.20.10-1.el8

almalinux advisories ALSA-2021:1804

  • mesa Rocky Linux 8 20.3.3-2.el8
  • libdrm Rocky Linux 8 2.4.103-1.el8
  • libX11 Rocky Linux 8 1.6.8-4.el8
  • libglvnd Rocky Linux 8 1:1.3.2-1.el8
  • libinput Rocky Linux 8 1.16.3-1.el8
  • libwacom Rocky Linux 8 1.6-2.el8
  • egl-wayland Rocky Linux 8 1.1.5-3.el8
  • xorg-x11-server Rocky Linux 8 1.20.10-1.el8

rocky linux advisories RLSA-2021:1804

  • libx11 Alpine 3.24, Alpine 3.23, Alpine 3.22 +13 more 1.6.12-r0

alpine advisories ALPINE-CVE-2020-14363

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-2020-14363 updated cvss 7.8

libX11: integer overflow leads to double free in locale handling

  • Red Hat Enterprise Linux 5 libX11
    affected: no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) xorg-x11-server-source 1.20.10-1.el8 Red Hat Enterprise Linux AppStream (v. 8) mesa 20.3.3-2.el8, libwacom 1.6-2.el8, libX11 1.6.8-4.el8, libdrm 2.4.103-1.el8, libglvnd 1.3.2-1.el8, libinput 1.16.3-1.el8, +28 more
    fixed: vendor fix RHSA-2021:1804
  • Red Hat Enterprise Linux Client (v. 7) libX11 1.6.7-3.el7_9, libX11-common 1.6.7-3.el7_9 Red Hat Enterprise Linux ComputeNode Optional (v. 7) libX11-devel 1.6.7-3.el7_9, libX11-debuginfo 1.6.7-3.el7_9
    fixed: vendor fix RHSA-2020:4908
  • Red Hat Enterprise Linux Desktop (v. 6) libX11 1.6.4-4.el6_10, libX11-common 1.6.4-4.el6_10 Red Hat Enterprise Linux Desktop Optional (v. 6) libX11-devel 1.6.4-4.el6_10, libX11-debuginfo 1.6.4-4.el6_10 Red Hat Enterprise Linux HPC Node (v. 6) libX11 1.6.4-4.el6_10, libX11-common 1.6.4-4.el6_10 Red Hat Enterprise Linux HPC Node Optional (v. 6) libX11-devel 1.6.4-4.el6_10, libX11-debuginfo 1.6.4-4.el6_10 Red Hat Enterprise Linux Server (v. 6) libX11 1.6.4-4.el6_10, libX11-common 1.6.4-4.el6_10
    fixed: vendor fix RHSA-2020:4946
  • Red Hat Enterprise Linux Server (v. 7) libX11 1.6.7-3.el7_9, libX11-common 1.6.7-3.el7_9
    fixed: vendor fix RHSA-2020:4908
  • Red Hat Enterprise Linux Workstation (v. 6) libX11 1.6.4-4.el6_10, libX11-common 1.6.4-4.el6_10
    fixed: vendor fix RHSA-2020:4946
  • Red Hat Enterprise Linux Workstation (v. 7) libX11 1.6.7-3.el7_9, libX11-common 1.6.7-3.el7_9
    fixed: vendor fix RHSA-2020:4908

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

0.56% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/Ruia-ruia/Exploits/blob/master/x11doublefree.sh referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P
OSV 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia Xorg_libX11_jll
<1.8.6+0
1.8.6+0

Affected products

  • The X11 Project libX11

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.