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Fencer Vulns
high 7.8

CVE-2021-4009 json

A flaw was found in xorg-x11-server in versions before 21.1.2 and before 1.20.14.

published 2021-12-17 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-33915

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

A flaw was found in xorg-x11-server in versions before 21.1.2 and before 1.20.14. An out-of-bounds access can occur in the SProcXFixesCreatePointerBarrier function. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Patch / fix

  • x.org x_server 1.20.14
  • xwayland Debian 14, Debian 13, Debian 12 2:21.1.4-1
  • xorg-server Debian 14, Debian 13, Debian 12 2:1.20.13-3

debian advisories DEBIAN-CVE-2021-4009

  • xwayland Ubuntu 22.04 LTS 2:21.1.3-1ubuntu1
  • xorg-server Ubuntu 18.04 LTS 2:1.19.6-1ubuntu4.10
  • xorg-server Ubuntu 20.04 LTS 2:1.20.13-1ubuntu1~20.04.2
  • xorg-server Ubuntu 22.04 LTS 2:1.20.13-1ubuntu2
  • xorg-server-hwe-18.04 Ubuntu 18.04 LTS 2:1.20.8-2ubuntu2.2~18.04.6
  • xorg-server Ubuntu Pro 14.04 LTS 2:1.15.1-0ubuntu2.11+esm5
  • xorg-server Ubuntu Pro 16.04 LTS 2:1.18.4-0ubuntu0.12+esm1
  • xorg-server-hwe-16.04 Ubuntu Pro 16.04 LTS 2:1.19.6-1ubuntu4.1~16.04.6+esm5

ubuntu advisories UBUNTU-CVE-2021-4009

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

  • xorg-x11-server RHEL 8 1.20.11-5.el8
  • xorg-x11-server-Xwayland RHEL 8 21.1.3-2.el8
  • xorg-x11-server-Xdmx RHEL 8 1.20.11-5.el8
  • xorg-x11-server-Xorg RHEL 8 1.20.11-5.el8
  • xorg-x11-server-Xvfb RHEL 8 1.20.11-5.el8
  • xorg-x11-server-Xnest RHEL 8 1.20.11-5.el8
  • xorg-x11-server-common RHEL 8 1.20.11-5.el8
  • xorg-x11-server-source RHEL 8 1.20.11-5.el8

red hat advisories RHSA-2022:1917RHSA-2022:0003

  • xorg-x11-server SLES 15 SP2-BCL, SLE Workstation Extension 15 SP3, SLE Real Time 15 SP2 +10 more 1.20.3-22.5.42.1
  • xorg-x11-server SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +4 more 7.6_1.18.3-76.46.1
  • xorg-x11-server SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +3 more 1.20.3-14.5.22.1
  • xorg-x11-server SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 1.19.6-8.36.1
  • xorg-x11-server SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 1.19.6-4.28.1
  • xorg-x11-server SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 1.19.6-10.29.1

suse advisories SUSE-SU-2021:4136-2SUSE-SU-2021:4136-1SUSE-SU-2021:4124-1SUSE-SU-2021:4122-1SUSE-SU-2021:4121-1SUSE-SU-2021:4120-1

  • xorg-x11-server openSUSE Tumbleweed 21.1.2-1.1
  • xwayland openSUSE Tumbleweed 21.1.4-1.1
  • xorg-x11-server openSUSE Leap 15.2 1.20.3-lp152.8.36.1
  • xorg-x11-server openSUSE Leap 15.3 1.20.3-22.5.42.1

opensuse advisories openSUSE-SU-2024:11685-1openSUSE-SU-2024:11699-1openSUSE-SU-2021:1606-1openSUSE-SU-2021:4136-1

  • xorg-x11-server-Xwayland AlmaLinux 8 21.1.3-2.el8
  • xorg-x11-server-Xdmx AlmaLinux 8 1.20.11-5.el8
  • xorg-x11-server-Xorg AlmaLinux 8 1.20.11-5.el8
  • xorg-x11-server-Xvfb AlmaLinux 8 1.20.11-5.el8
  • xorg-x11-server-Xnest AlmaLinux 8 1.20.11-5.el8
  • xorg-x11-server-common AlmaLinux 8 1.20.11-5.el8
  • xorg-x11-server-source AlmaLinux 8 1.20.11-5.el8
  • xorg-x11-server-Xephyr AlmaLinux 8 1.20.11-5.el8

almalinux advisories ALSA-2022:1917

  • xorg-x11-server Rocky Linux 8 1.20.11-5.el8
  • xorg-x11-server-Xwayland Rocky Linux 8 21.1.3-2.el8

rocky linux advisories RLSA-2022:1917

  • xwayland Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 21.1.4-r0
  • xorg-server Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 21.1.2-r0

alpine advisories ALPINE-CVE-2021-4009

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

  • xorg-server Arch Linux 21.1.2-1
  • xorg-xwayland Arch Linux 21.1.4-1

arch linux advisories AVG-2636AVG-2640

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-2021-4009 updated cvss 7.8

xorg-x11-server: SProcXFixesCreatePointerBarrier out-of-bounds access

  • Red Hat Enterprise Linux 6 xorg-x11-server, xorg-x11-server-Xdmx, xorg-x11-server-Xorg, xorg-x11-server-Xvfb, xorg-x11-server-Xnest, xorg-x11-server-common, +2 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) xorg-x11-server 1.20.11-5.el8, xorg-x11-server-Xdmx 1.20.11-5.el8, xorg-x11-server-Xorg 1.20.11-5.el8, xorg-x11-server-Xvfb 1.20.11-5.el8, xorg-x11-server-Xnest 1.20.11-5.el8, xorg-x11-server-common 1.20.11-5.el8, +2 more
    fixed: vendor fix RHSA-2022:1917
  • Red Hat Enterprise Linux Client (v. 7) xorg-x11-server 1.20.4-17.el7_9, xorg-x11-server-Xorg 1.20.4-17.el7_9, xorg-x11-server-common 1.20.4-17.el7_9, xorg-x11-server-Xephyr 1.20.4-17.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) xorg-x11-server-Xdmx 1.20.4-17.el7_9, xorg-x11-server-Xvfb 1.20.4-17.el7_9, xorg-x11-server-Xnest 1.20.4-17.el7_9, xorg-x11-server-source 1.20.4-17.el7_9, xorg-x11-server-Xwayland 1.20.4-17.el7_9 Red Hat Enterprise Linux ComputeNode Optional (v. 7) xorg-x11-server 1.20.4-17.el7_9, xorg-x11-server-Xdmx 1.20.4-17.el7_9, xorg-x11-server-Xorg 1.20.4-17.el7_9, xorg-x11-server-Xvfb 1.20.4-17.el7_9, xorg-x11-server-Xnest 1.20.4-17.el7_9, xorg-x11-server-common 1.20.4-17.el7_9, +3 more
    fixed: vendor fix RHSA-2022:0003
  • Red Hat Enterprise Linux CRB (v. 8) xorg-x11-server-source 1.20.11-5.el8
    fixed: vendor fix RHSA-2022:1917
  • Red Hat Enterprise Linux Server (v. 7) xorg-x11-server 1.20.4-17.el7_9, xorg-x11-server-Xorg 1.20.4-17.el7_9, xorg-x11-server-common 1.20.4-17.el7_9, xorg-x11-server-Xephyr 1.20.4-17.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) xorg-x11-server-Xdmx 1.20.4-17.el7_9, xorg-x11-server-Xvfb 1.20.4-17.el7_9, xorg-x11-server-Xnest 1.20.4-17.el7_9, xorg-x11-server-source 1.20.4-17.el7_9, xorg-x11-server-Xwayland 1.20.4-17.el7_9 Red Hat Enterprise Linux Workstation (v. 7) xorg-x11-server 1.20.4-17.el7_9, xorg-x11-server-Xorg 1.20.4-17.el7_9, xorg-x11-server-common 1.20.4-17.el7_9, xorg-x11-server-Xephyr 1.20.4-17.el7_9 Red Hat Enterprise Linux Workstation Optional (v. 7) xorg-x11-server-Xdmx 1.20.4-17.el7_9, xorg-x11-server-Xvfb 1.20.4-17.el7_9, xorg-x11-server-Xnest 1.20.4-17.el7_9, xorg-x11-server-source 1.20.4-17.el7_9, xorg-x11-server-Xwayland 1.20.4-17.el7_9
    fixed: vendor fix RHSA-2022:0003
  • Red Hat Enterprise Linux 9 xorg-x11-server, xorg-x11-server-Xdmx, xorg-x11-server-Xorg, xorg-x11-server-Xvfb, xorg-x11-server-Xnest, xorg-x11-server-common, +3 more
    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

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
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 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a xorg-x11-server

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

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.