1. Ubuntu Security Notices
  2. USN-7940-1

USN-7940-1: Linux kernel (Azure FIPS) vulnerabilities

Publication date

17 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:

  • ARM64 architecture;
  • PowerPC architecture;
  • x86 architecture;
  • Cryptographic API;
  • ACPI drivers;
  • Ublk userspace block driver;
  • Clock framework and drivers;
  • EDAC drivers;
  • GPU drivers;
  • HSI subsystem;
  • IIO subsystem;
  • InfiniBand drivers;
  • Media...

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:

  • ARM64 architecture;
  • PowerPC architecture;
  • x86 architecture;
  • Cryptographic API;
  • ACPI drivers;
  • Ublk userspace block driver;
  • Clock framework and drivers;
  • EDAC drivers;
  • GPU drivers;
  • HSI subsystem;
  • IIO subsystem;
  • InfiniBand drivers;
  • Media drivers;
  • MemoryStick subsystem;
  • Network drivers;
  • NTB driver;
  • PCI subsystem;
  • Remote Processor subsystem;
  • Thermal drivers;
  • Virtio Host (VHOST) subsystem;
  • 9P distributed file system;
  • File systems infrastructure;
  • JFS file system;
  • Network file system (NFS) server daemon;
  • NTFS3 file system;
  • SMB network file system;
  • Memory management;
  • Bluetooth subsystem;
  • RDMA verbs API;
  • Kernel fork() syscall;
  • Timer subsystem;
  • Tracing infrastructure;
  • Watch queue notification mechanism;
  • Appletalk network protocol;
  • Asynchronous Transfer Mode (ATM) subsystem;
  • Networking core;
  • IPv4 networking;
  • IPv6 networking;
  • Netfilter;
  • Network traffic control;
  • SCTP protocol;
  • TLS protocol;
  • SoC Audio for Freescale CPUs drivers

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-fips –  6.8.0-1044.50+fips1  
linux-image-azure-fips –  6.8.0-1044.50+fips1  
linux-image-azure-fips-6.8 –  6.8.0-1044.50+fips1  

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References

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