USN-6555-2: X.Org X Server vulnerabilities

USN-6555-1 fixed several vulnerabilities in X.Org. This update provides
the corresponding update for Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.

Original advisory details:

Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled XKB
button actions. An attacker could possibly use this issue to cause the X
Server to crash, execute arbitrary code, or escalate privileges.
(CVE-2023-6377)

Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
memory when processing the RRChangeOutputProperty and
RRChangeProviderProperty APIs. An attacker could possibly use …

actions advisory arbitrary code attacker button code crash issue lts org server ubuntu update usn vulnerabilities x.org