1. Ubuntu Security Notices
  2. USN-7935-1

USN-7935-1: Linux kernel (Azure) vulnerabilities

Publication date

15 December 2025

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

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. (CVE-2025-40300)

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;
  • HSI subsystem;
  • Media drivers;
  • Network drivers;
  • Bluetooth subsystem;
  • Timer subsystem;
  • Memory management;
  • Appletalk network protocol;
  • Netfilter;
  • TLS protocol

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. (CVE-2025-40300)

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;
  • HSI subsystem;
  • Media drivers;
  • Network drivers;
  • Bluetooth subsystem;
  • Timer subsystem;
  • Memory management;
  • Appletalk network protocol;
  • Netfilter;
  • TLS protocol

Update instructions

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

Learn more about how to get the fixes.

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.

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

Ubuntu Release Package Version
24.04 LTS noble linux-image-6.8.0-1044-azure –  6.8.0-1044.50
linux-image-azure-6.8 –  6.8.0-1044.50
linux-image-azure-lts-24.04 –  6.8.0-1044.50
22.04 LTS jammy linux-image-6.8.0-1044-azure –  6.8.0-1044.50~22.04.1
linux-image-azure –  6.8.0-1044.50~22.04.1
linux-image-azure-6.8 –  6.8.0-1044.50~22.04.1

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References

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