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Ubuntu Security Notice USN-3758-2
August 30, 2018

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

- Ubuntu 12.04 ESM

Summary:

Several security issues were fixed in libx11.

Software Description:
- libx11: X11 client-side library

Details:

USN-3758-1 fixed several vulnerabilities in libx11. This update
provides the corresponding update for Ubuntu 12.04 ESM.

Original advisory details:

 Tobias Stoeckmann discovered that libx11 incorrectly handled certain
 images. An attacker could possibly use this issue to access sensitive
 information (CVE-2016-7942)

 Tobias Stoeckmann discovered that libx11 incorrectly handled certain
 inputs. An attacker could possibly use this issue to access sensitive
 information. (CVE-2016-7943)

 It was discovered that libx11 incorrectly handled certain inputs.
 An attacker could possibly use this issue to cause a denial of
 service. (CVE-2018-14598, CVE-2018-14599, CVE-2018-14600)

Update instructions:

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

Ubuntu 12.04 ESM:
  libx11-6                        2:1.4.99.1-0ubuntu2.4
  libx11-dev                      2:1.4.99.1-0ubuntu2.4

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

References:
  https://usn.ubuntu.com/usn/usn-3758-2
  https://usn.ubuntu.com/usn/usn-3758-1
  CVE-2016-7942, CVE-2016-7943, CVE-2018-14598, CVE-2018-14599,
  CVE-2018-14600