1. Ubuntu Security Notices
  2. USN-7863-1

USN-7863-1: Linux kernel vulnerabilities

Publication date

6 November 2025

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-kvm - Linux kernel for cloud environments
  • linux-lts-xenial - Linux hardware enablement kernel from Xenial for Trusty

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;
  • TTY drivers;
  • Ext4 file system;
  • Timer subsystem;
  • DCCP (Datagram Congestion Control Protocol);
  • IPv6 networking;
  • NET/ROM layer;
  • SCTP protocol;
  • USB sound devices

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;
  • TTY drivers;
  • Ext4 file system;
  • Timer subsystem;
  • DCCP (Datagram Congestion Control Protocol);
  • IPv6 networking;
  • NET/ROM layer;
  • SCTP protocol;
  • USB sound devices

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
16.04 LTS xenial linux-image-4.4.0-1150-kvm –  4.4.0-1150.161  
linux-image-4.4.0-1187-aws –  4.4.0-1187.202  
linux-image-4.4.0-274-generic –  4.4.0-274.308  
linux-image-4.4.0-274-lowlatency –  4.4.0-274.308  
linux-image-aws –  4.4.0.1187.191  
linux-image-generic –  4.4.0.274.280  
linux-image-generic-lts-xenial –  4.4.0.274.280  
linux-image-kvm –  4.4.0.1150.147  
linux-image-lowlatency –  4.4.0.274.280  
linux-image-lowlatency-lts-xenial –  4.4.0.274.280  
linux-image-virtual –  4.4.0.274.280  
linux-image-virtual-lts-xenial –  4.4.0.274.280  
14.04 LTS trusty linux-image-4.4.0-1149-aws –  4.4.0-1149.155  
linux-image-4.4.0-274-generic –  4.4.0-274.308~14.04.1  
linux-image-4.4.0-274-lowlatency –  4.4.0-274.308~14.04.1  
linux-image-aws –  4.4.0.1149.146  
linux-image-generic-lts-xenial –  4.4.0.274.308~14.04.1  
linux-image-lowlatency-lts-xenial –  4.4.0.274.308~14.04.1  
linux-image-virtual-lts-xenial –  4.4.0.274.308~14.04.1  

Reduce your security exposure

Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

Get Ubuntu Pro

References

id="usn"

Have additional questions?

Talk to a member of the team ›