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Ubuntu Security Notice USN-6587-4
February 01, 2024
xorg-server, xwayland regression
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A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 18.04 LTS (Available with Ubuntu Pro)
- Ubuntu 16.04 LTS (Available with Ubuntu Pro)
Summary:
A regression was fixed in X.Org X Server.
Software Description:
- xorg-server: X.Org X11 server
Details:
USN-6587-1 fixed vulnerabilities in X.Org X Server. The fix was incomplete
resulting in a possible regression. This update fixes the problem.
Original advisory details:
 Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
 memory when processing the DeviceFocusEvent and ProcXIQueryPointer APIs. An
 attacker could possibly use this issue to cause the X Server to crash,
 obtain sensitive information, or execute arbitrary code. (CVE-2023-6816)
 Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
 reattaching to a different master device. An attacker could use this issue
 to cause the X Server to crash, leading to a denial of service, or possibly
 execute arbitrary code. (CVE-2024-0229)
 Olivier Fourdan and Donn Seeley discovered that the X.Org X Server
 incorrectly labeled GLX PBuffers when used with SELinux. An attacker could
 use this issue to cause the X Server to crash, leading to a denial of
 service. (CVE-2024-0408)
 Olivier Fourdan discovered that the X.Org X Server incorrectly handled
 the curser code when used with SELinux. An attacker could use this issue to
 cause the X Server to crash, leading to a denial of service.
 (CVE-2024-0409)
 Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
 memory when processing the XISendDeviceHierarchyEvent API. An attacker
 could possibly use this issue to cause the X Server to crash, or execute
 arbitrary code. (CVE-2024-21885)
 Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
 devices being disabled. An attacker could possibly use this issue to cause
 the X Server to crash, or execute arbitrary code. (CVE-2024-21886)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 18.04 LTS (Available with Ubuntu Pro):
  xserver-xorg-core               2:1.19.6-1ubuntu4.15+esm5
  xwayland                        2:1.19.6-1ubuntu4.15+esm5
Ubuntu 16.04 LTS (Available with Ubuntu Pro):
  xserver-xorg-core               2:1.18.4-0ubuntu0.12+esm10
  xwayland                        2:1.18.4-0ubuntu0.12+esm10
After a standard system update you need to reboot your computer to make all
the necessary changes.
References:
  https://ubuntu.com/security/notices/USN-6587-4
  https://ubuntu.com/security/notices/USN-6587-1
  https://launchpad.net/bugs/2051536