A libx11 security update has been released for Ubuntu Linux 20.04 LTS, 22.04 LTS, and 23.04.

[USN-6407-1] libx11 vulnerabilities

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Ubuntu Security Notice USN-6407-1
October 03, 2023

libx11 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 23.04
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in libx11.

Software Description:
- libx11: X11 client-side library

Details:

Gregory James Duck discovered that libx11 incorrectly handled certain
keyboard symbols. If a user were tricked into connecting to a malicious X
server, a remote attacker could use this issue to cause libx11 to crash,
resulting in a denial of service, or possibly execute arbitrary code.
(CVE-2023-43785)

Yair Mizrahi discovered that libx11 incorrectly handled certain malformed
XPM image files. If a user were tricked into opening a specially crafted
XPM image file, a remote attacker could possibly use this issue to consume
memory, leading to a denial of service. (CVE-2023-43786)

Yair Mizrahi discovered that libx11 incorrectly handled certain malformed
XPM image files. If a user were tricked into opening a specially crafted
XPM image file, a remote attacker could use this issue to cause libx11 to
crash, leading to a denial of service, or possibly execute arbitrary code.
(CVE-2023-43787)

Update instructions:

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

Ubuntu 23.04:
libx11-6 2:1.8.4-2ubuntu0.3

Ubuntu 22.04 LTS:
libx11-6 2:1.7.5-1ubuntu0.3

Ubuntu 20.04 LTS:
libx11-6 2:1.6.9-2ubuntu1.6

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

References:
https://ubuntu.com/security/notices/USN-6407-1
CVE-2023-43785, CVE-2023-43786, CVE-2023-43787

Package Information:
https://launchpad.net/ubuntu/+source/libx11/2:1.8.4-2ubuntu0.3
https://launchpad.net/ubuntu/+source/libx11/2:1.7.5-1ubuntu0.3
https://launchpad.net/ubuntu/+source/libx11/2:1.6.9-2ubuntu1.6