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Ubuntu 24.04 LTS USN-7860-2: Linux Kernel Vulnerability CVE-2025-40300

ubuntu
Calendar Grey November 6, 2025
Dist Ubuntu Esm H88
Ubuntu 24.04 LTS has a critical kernel flaw (CVE-2025-40300) exposing sensitive information, requiring immediate update.
The system could be made to expose sensitive information.

Summary

The system could be made to expose sensitive information.

Software Description:

- 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.

Topics%20covered

Topics Covered

security advisory critical Ubuntu Linux kernel sensitive information Real Time

Update Instructions

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

Ubuntu 24.04 LTS
   linux-image-6.14.0-1015-realtime  6.14.0-1015.15~24.04.1
                                   Available with Ubuntu Pro
   linux-image-realtime-6.14       6.14.0-1015.15~24.04.1
                                   Available with Ubuntu Pro
   linux-image-realtime-hwe-24.04  6.14.0-1015.15~24.04.1
                                   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-7860-2

https://ubuntu.com/security/notices/USN-7860-1

CVE-2025-40300

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-7860-2

Topics%20covered

Topics Covered

security advisory critical Ubuntu Linux kernel sensitive information Real Time

Package Information

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