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Ubuntu 18.04 LTS: Major Linux Kernel Security Issues VMSCAPE CVE-2025-40300

ubuntu
Calendar Grey November 7, 2025
Dist Ubuntu Esm H88
A critical update for Ubuntu kernel addresses multiple security flaws, crucial for safeguarding Azure cloud systems.
Several security issues were fixed in the Linux kernel.

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;

...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory Ubuntu kernel information exposure cloud insufficient isolation

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

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-7853-3

Topics%20covered

Topics Covered

security advisory Ubuntu kernel information exposure cloud insufficient isolation

Package Information

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