==========================================================================
Ubuntu Security Notice USN-5465-1
June 08, 2022

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

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

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 the Linux kernel did not properly restrict access to
the kernel debugger when booted in secure boot environments. A privileged
attacker could use this to bypass UEFI Secure Boot restrictions.
(CVE-2022-21499)

Aaron Adams discovered that the netfilter subsystem in the Linux kernel did
not properly handle the removal of stateful expressions in some situations,
leading to a use-after-free vulnerability. A local attacker could use this
to cause a denial of service (system crash) or execute arbitrary code.
(CVE-2022-1966)

Jann Horn discovered that the Linux kernel did not properly enforce seccomp
restrictions in some situations. A local attacker could use this to bypass
intended seccomp sandbox restrictions. (CVE-2022-30594)

Update instructions:

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

Ubuntu 16.04 ESM:
  linux-image-4.4.0-1108-kvm      4.4.0-1108.118
  linux-image-4.4.0-1143-aws      4.4.0-1143.158
  linux-image-4.4.0-227-generic   4.4.0-227.261
  linux-image-4.4.0-227-lowlatency  4.4.0-227.261
  linux-image-aws                 4.4.0.1143.147
  linux-image-generic             4.4.0.227.233
  linux-image-kvm                 4.4.0.1108.105
  linux-image-lowlatency          4.4.0.227.233
  linux-image-virtual             4.4.0.227.233

Ubuntu 14.04 ESM:
  linux-image-4.4.0-1107-aws      4.4.0-1107.113
  linux-image-4.4.0-227-generic   4.4.0-227.261~14.04.1
  linux-image-4.4.0-227-lowlatency  4.4.0-227.261~14.04.1
  linux-image-aws                 4.4.0.1107.104
  linux-image-generic-lts-xenial  4.4.0.227.197
  linux-image-lowlatency-lts-xenial  4.4.0.227.197
  linux-image-virtual-lts-xenial  4.4.0.227.197

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-5465-1
  CVE-2022-1966, CVE-2022-21499, CVE-2022-30594