[USN-7860-3] Linux kernel (FIPS) vulnerability

[Rodrigo Figueiredo Zaiden]

==========================================================================
Ubuntu Security Notice USN-7860-3
November 07, 2025

linux-fips, linux-aws-fips, inux-gcp-fips vulnerability
==========================================================================

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

- Ubuntu 22.04 LTS

Summary:

The system could be made to expose sensitive information.

Software Description:
- linux-aws-fips: Linux kernel for Amazon Web Services (AWS) systems with FIPS
- linux-fips: Linux kernel with FIPS
- linux-gcp-fips: Linux kernel for Google Cloud Platform (GCP) systems with 
FIPS

Details:

Jean-Claude Graf, Sandro Rüegge, Ali Hajiabadi, and Kaveh Razavi discovered
that the Linux kernel contained insufficient branch predictor isolation
between a guest and a userspace hypervisor for certain processors. This
flaw is known as VMSCAPE. An attacker in a guest VM could possibly use this
to expose sensitive information from the host OS.

Update instructions:

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

Ubuntu 22.04 LTS
   linux-image-5.15.0-1096-aws-fips  5.15.0-1096.103+fips1
                                   Available with Ubuntu Pro
   linux-image-5.15.0-1096-gcp-fips  5.15.0-1096.105+fips1
                                   Available with Ubuntu Pro
   linux-image-5.15.0-161-fips     5.15.0-161.171+fips1
                                   Available with Ubuntu Pro
   linux-image-aws-fips            5.15.0.1096.92
                                   Available with Ubuntu Pro
   linux-image-aws-fips-5.15       5.15.0.1096.92
                                   Available with Ubuntu Pro
   linux-image-fips                5.15.0.161.93
                                   Available with Ubuntu Pro
   linux-image-fips-5.15           5.15.0.161.93
                                   Available with Ubuntu Pro
   linux-image-gcp-fips            5.15.0.1096.86
                                   Available with Ubuntu Pro
   linux-image-gcp-fips-5.15       5.15.0.1096.86
                                   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-7860-3
   https://ubuntu.com/security/notices/USN-7860-2
   https://ubuntu.com/security/notices/USN-7860-1
   CVE-2025-40300

Package Information:
   https://launchpad.net/ubuntu/+source/linux-aws-fips/5.15.0-1096.103+fips1
   https://launchpad.net/ubuntu/+source/linux-fips/5.15.0-161.171+fips1
   https://launchpad.net/ubuntu/+source/linux-gcp-fips/5.15.0-1096.105+fips1

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