Ubuntu Security Notices
USN-7860-2

USN-7860-2: Linux kernel (Real-time) vulnerability

Publication date

6 November 2025

Overview

The system could be made to expose sensitive information.

Releases

24.04 LTS

Packages

linux-realtime-6.14 - Linux kernel for Real-time 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.

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-6.14.0-1015-realtime – 6.14.0-1015.15~24.04.1
	linux-image-realtime-6.14 – 6.14.0-1015.15~24.04.1
	linux-image-realtime-hwe-24.04 – 6.14.0-1015.15~24.04.1

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References

CVE-2025-40300

CVE-2025-40300

Have additional questions?

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