[USN-7853-3] Linux kernel (Azure) vulnerabilities

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==========================================================================
Ubuntu Security Notice USN-7853-3
November 07, 2025

linux-azure, linux-azure-4.15 vulnerabilities
==========================================================================

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

- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-azure-4.15: Linux kernel for Microsoft Azure Cloud systems
- linux-azure: Linux kernel for Microsoft Azure Cloud systems

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:
- DMA engine subsystem;
- GPU drivers;
- HSI subsystem;
- Ethernet team driver;
- Ext4 file system;
- Timer subsystem;
- DCCP (Datagram Congestion Control Protocol);
- IPv6 networking;
- NET/ROM layer;
- SCTP protocol;
- USB sound devices;
(CVE-2023-52574, CVE-2023-52650, CVE-2024-41006, CVE-2024-50006,
CVE-2024-50299, CVE-2024-53124, CVE-2024-53150, CVE-2024-56767,
CVE-2025-37838, CVE-2025-38352)

Update instructions:

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

Ubuntu 18.04 LTS
linux-image-4.15.0-1194-azure 4.15.0-1194.209
Available with Ubuntu Pro
linux-image-azure-4.15 4.15.0.1194.162
Available with Ubuntu Pro
linux-image-azure-lts-18.04 4.15.0.1194.162
Available with Ubuntu Pro

Ubuntu 16.04 LTS
linux-image-4.15.0-1194-azure 4.15.0-1194.209~16.04.1
Available with Ubuntu Pro
linux-image-azure 4.15.0.1194.209~16.04.1
Available with Ubuntu Pro

Ubuntu 14.04 LTS
linux-image-4.15.0-1194-azure 4.15.0-1194.209~14.04.1
Available with Ubuntu Pro
linux-image-azure 4.15.0.1194.209~14.04.1
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-7853-3
https://ubuntu.com/security/notices/USN-7853-2
https://ubuntu.com/security/notices/USN-7853-1
CVE-2023-52574, CVE-2023-52650, CVE-2024-41006, CVE-2024-50006,
CVE-2024-50299, CVE-2024-53124, CVE-2024-53150, CVE-2024-56767,
CVE-2025-37838, CVE-2025-38352, CVE-2025-40300