[USN-7299-4] X.Org X Server regression

[Leonidas S. Barbosa]

==========================================================================
Ubuntu Security Notice USN-7299-4
March 17, 2025

xorg-server, xorg-server-hwe-16.04, xorg-server-hwe-18.04 regression
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in X.Org X Server.

Software Description:
- xorg-server: X.Org X11 server
- xorg-server-hwe-18.04: X.Org X11 server
- xorg-server-hwe-16.04: X.Org X11 server

Details:

USN-7299-2 fix vulnerabilities in X.Org X Server. This fix caused
a regression in Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. This update
fix the regression and re-apply the fix for the CVE listed.

We apologize for the inconvenience.

Original advisory details:

 Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
 certain memory operations. An attacker could use these issues to cause the
 X Server to crash, leading to a denial of service, or possibly execute
 arbitrary code.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS
  xserver-xorg-core               2:1.19.6-1ubuntu4.15+esm12
                                  Available with Ubuntu Pro
  xserver-xorg-core-hwe-18.04     2:1.20.8-2ubuntu2.2~18.04.11+esm4
                                  Available with Ubuntu Pro
  xwayland                        2:1.19.6-1ubuntu4.15+esm12
                                  Available with Ubuntu Pro
  xwayland-hwe-18.04              2:1.20.8-2ubuntu2.2~18.04.11+esm4
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  xserver-xorg-core               2:1.18.4-0ubuntu0.12+esm17
                                  Available with Ubuntu Pro
  xserver-xorg-core-hwe-16.04     2:1.19.6-1ubuntu4.1~16.04.6+esm9
                                  Available with Ubuntu Pro
  xwayland                        2:1.18.4-0ubuntu0.12+esm17
                                  Available with Ubuntu Pro
  xwayland-hwe-16.04              2:1.19.6-1ubuntu4.1~16.04.6+esm9
                                  Available with Ubuntu Pro

After a standard system update you need to reboot your computer to make all
the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-7299-4
  https://ubuntu.com/security/notices/USN-7299-3
  https://ubuntu.com/security/notices/USN-7299-2
  https://ubuntu.com/security/notices/USN-7299-1
  CVE-2025-26594, CVE-2025-26595, CVE-2025-26596, CVE-2025-26597,
  CVE-2025-26598, CVE-2025-26599, CVE-2025-26600, CVE-2025-26601,
  https://launchpad.net/bugs/2102209

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