==========================================================================
Ubuntu Security Notice USN-6646-1
February 20, 2024

linux, linux-aws, linux-kvm, linux-lts-xenial vulnerabilities
==========================================================================

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

- Ubuntu 16.04 LTS (Available with Ubuntu Pro)
- Ubuntu 14.04 LTS (Available with Ubuntu Pro)

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-kvm: Linux kernel for cloud environments
- linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty

Details:

It was discovered that a race condition existed in the ATM (Asynchronous
Transfer Mode) subsystem of the Linux kernel, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-51780)

It was discovered that a race condition existed in the Rose X.25 protocol
implementation in the Linux kernel, leading to a use-after- free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-51782)

It was discovered that the netfilter connection tracker for netlink in the
Linux kernel did not properly perform reference counting in some error
conditions. A local attacker could possibly use this to cause a denial of
service (memory exhaustion). (CVE-2023-7192)

Update instructions:

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

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   linux-image-4.4.0-1129-kvm      4.4.0-1129.139
   linux-image-4.4.0-1166-aws      4.4.0-1166.181
   linux-image-4.4.0-251-generic   4.4.0-251.285
   linux-image-4.4.0-251-lowlatency  4.4.0-251.285
   linux-image-aws                 4.4.0.1166.170
   linux-image-generic             4.4.0.251.257
   linux-image-generic-lts-xenial  4.4.0.251.257
   linux-image-kvm                 4.4.0.1129.126
   linux-image-lowlatency          4.4.0.251.257
   linux-image-lowlatency-lts-xenial  4.4.0.251.257
   linux-image-virtual             4.4.0.251.257
   linux-image-virtual-lts-xenial  4.4.0.251.257

Ubuntu 14.04 LTS (Available with Ubuntu Pro):
   linux-image-4.4.0-1128-aws      4.4.0-1128.134
   linux-image-4.4.0-251-generic   4.4.0-251.285~14.04.1
   linux-image-4.4.0-251-lowlatency  4.4.0-251.285~14.04.1
   linux-image-aws                 4.4.0.1128.125

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

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
   https://ubuntu.com/security/notices/USN-6646-1
   CVE-2023-51780, CVE-2023-51782, CVE-2023-7192