==========================================================================
Ubuntu Security Notice USN-8392-1
June 04, 2026

linux-aws-5.4, linux-hwe-5.4 vulnerabilities
==========================================================================

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

- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-aws-5.4: Linux kernel for Amazon Web Services (AWS) systems
- linux-hwe-5.4: Linux hardware enablement (HWE) kernel

Details:

It was discovered that the Linux kernel algif_aead module did not properly
handle in-place cryptographic operations. This flaw is known as Copy Fail.
A local attacker could use this to escalate privileges, or possibly escape
a container. (CVE-2026-31431)

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:
   - Cryptographic API;
   - Packet sockets;
   - RDS protocol;
   - TLS protocol;
(CVE-2026-31504, CVE-2026-31533, CVE-2026-43033, CVE-2026-43077,
CVE-2026-43078, CVE-2026-43494, CVE-2026-46028)

Update instructions:

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

Ubuntu 18.04 LTS
   linux-image-5.4.0-1160-aws      5.4.0-1160.170~18.04.1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-231-generic   5.4.0-231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-5.4.0-231-lowlatency  5.4.0-231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-aws                 5.4.0.1160.170~18.04.1
                                   Available with Ubuntu Pro
   linux-image-aws-5.4             5.4.0.1160.170~18.04.1
                                   Available with Ubuntu Pro
   linux-image-generic-5.4         5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-generic-hwe-18.04   5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-lowlatency-5.4      5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-lowlatency-hwe-18.04  5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-oem                 5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-oem-osp1            5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-snapdragon-5.4      5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-snapdragon-hwe-18.04  5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-virtual-5.4         5.4.0.231.251~18.04.1
                                   Available with Ubuntu Pro
   linux-image-virtual-hwe-18.04   5.4.0.231.251~18.04.1
                                   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-8392-1
   CVE-2026-31431, CVE-2026-31504, CVE-2026-31533, CVE-2026-43033,
   CVE-2026-43077, CVE-2026-43078, CVE-2026-43284, CVE-2026-43494,
   CVE-2026-43500, CVE-2026-46028