==========================================================================
Ubuntu Security Notice USN-8389-1
June 04, 2026

linux, linux-aws, linux-aws-fips, linux-azure, linux-azure-5.4,
linux-azure-fips, linux-bluefield, linux-fips, linux-gcp, linux-gcp-5.4,
linux-gcp-fips, linux-iot, linux-kvm, linux-oracle, linux-oracle-5.4,
linux-xilinx-zynqmp vulnerabilities
==========================================================================

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

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

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-aws-fips: Linux kernel for Amazon Web Services (AWS) systems with FIPS
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-azure-fips: Linux kernel for Microsoft Azure Cloud systems with FIPS
- linux-bluefield: Linux kernel for NVIDIA BlueField platforms
- linux-fips: Linux kernel with FIPS
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-gcp-fips: Linux kernel for Google Cloud Platform (GCP) systems with 
FIPS
- linux-iot: Linux kernel for IoT platforms
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems
- linux-xilinx-zynqmp: Linux kernel for Xilinx ZynqMP processors
- linux-azure-5.4: Linux kernel for Microsoft Azure cloud systems
- linux-gcp-5.4: Linux kernel for Google Cloud Platform (GCP) systems
- linux-oracle-5.4: Linux kernel for Oracle Cloud systems

Details:

It was discovered that the Linux kernel did not properly handle shared page
fragments during socket buffer operations, collectively known as Dirty
Frag. A logic flaw existed in the XFRM ESP-in-TCP subsystem and in the
RxRPC networking subsystem when processing paged fragments. A local
attacker could use this to escalate privileges, or possibly escape a
container. (CVE-2026-43284, CVE-2026-43500)

Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
   - RDS protocol;
(CVE-2026-43494)

Update instructions:

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

Ubuntu 20.04 LTS
   linux-image-5.4.0-1064-iot      5.4.0-1064.67
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1078-xilinx-zynqmp  5.4.0-1078.82
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1119-bluefield  5.4.0-1119.126
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1134-fips     5.4.0-1134.144
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1147-kvm      5.4.0-1147.156
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1158-oracle   5.4.0-1158.168
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1160-aws      5.4.0-1160.170
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1160-aws-fips  5.4.0-1160.170+fips1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1163-gcp      5.4.0-1163.172
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1163-gcp-fips  5.4.0-1163.172+fips1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1164-azure    5.4.0-1164.170
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1164-azure-fips  5.4.0-1164.170+fips1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-231-generic   5.4.0-231.251
                                   Available with Ubuntu Pro
   linux-image-5.4.0-231-generic-lpae  5.4.0-231.251
                                   Available with Ubuntu Pro
   linux-image-5.4.0-231-lowlatency  5.4.0-231.251
                                   Available with Ubuntu Pro
   linux-image-aws-5.4             5.4.0.1160.157
                                   Available with Ubuntu Pro
   linux-image-aws-fips            5.4.0.1160.107
                                   Available with Ubuntu Pro
   linux-image-aws-fips-5.4        5.4.0.1160.107
                                   Available with Ubuntu Pro
   linux-image-aws-lts-20.04       5.4.0.1160.157
                                   Available with Ubuntu Pro
   linux-image-azure-5.4           5.4.0.1164.156
                                   Available with Ubuntu Pro
   linux-image-azure-fips          5.4.0.1164.100
                                   Available with Ubuntu Pro
   linux-image-azure-fips-5.4      5.4.0.1164.100
                                   Available with Ubuntu Pro
   linux-image-azure-lts-20.04     5.4.0.1164.156
                                   Available with Ubuntu Pro
   linux-image-bluefield           5.4.0.1119.115
                                   Available with Ubuntu Pro
   linux-image-bluefield-5.4       5.4.0.1119.115
                                   Available with Ubuntu Pro
   linux-image-fips                5.4.0.1134.131
                                   Available with Ubuntu Pro
   linux-image-fips-5.4            5.4.0.1134.131
                                   Available with Ubuntu Pro
   linux-image-gcp-5.4             5.4.0.1163.165
                                   Available with Ubuntu Pro
   linux-image-gcp-fips            5.4.0.1163.105
                                   Available with Ubuntu Pro
   linux-image-gcp-fips-5.4        5.4.0.1163.105
                                   Available with Ubuntu Pro
   linux-image-gcp-lts-20.04       5.4.0.1163.165
                                   Available with Ubuntu Pro
   linux-image-generic             5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-generic-5.4         5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-generic-lpae        5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-generic-lpae-5.4    5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-kvm                 5.4.0.1147.143
                                   Available with Ubuntu Pro
   linux-image-kvm-5.4             5.4.0.1147.143
                                   Available with Ubuntu Pro
   linux-image-lowlatency          5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-lowlatency-5.4      5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-oem                 5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-oem-osp1            5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-oracle-5.4          5.4.0.1158.152
                                   Available with Ubuntu Pro
   linux-image-oracle-lts-20.04    5.4.0.1158.152
                                   Available with Ubuntu Pro
   linux-image-virtual             5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-virtual-5.4         5.4.0.231.223
                                   Available with Ubuntu Pro
   linux-image-xilinx-zynqmp       5.4.0.1078.78
                                   Available with Ubuntu Pro
   linux-image-xilinx-zynqmp-5.4   5.4.0.1078.78
                                   Available with Ubuntu Pro

Ubuntu 18.04 LTS
   linux-image-5.4.0-1158-oracle   5.4.0-1158.168~18.04.1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1163-gcp      5.4.0-1163.172~18.04.1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-1164-azure    5.4.0-1164.170~18.04.1
                                   Available with Ubuntu Pro
   linux-image-azure               5.4.0.1164.170~18.04.1
                                   Available with Ubuntu Pro
   linux-image-azure-5.4           5.4.0.1164.170~18.04.1
                                   Available with Ubuntu Pro
   linux-image-gcp                 5.4.0.1163.172~18.04.1
                                   Available with Ubuntu Pro
   linux-image-gcp-5.4             5.4.0.1163.172~18.04.1
                                   Available with Ubuntu Pro
   linux-image-oracle              5.4.0.1158.168~18.04.1
                                   Available with Ubuntu Pro
   linux-image-oracle-5.4          5.4.0.1158.168~18.04.1
                                   Available with Ubuntu Pro

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-8389-1
   CVE-2026-43284, CVE-2026-43494, CVE-2026-43500