1. Ubuntu Security Notices
  2. USN-8966-1

USN-8966-1: Linux kernel vulnerabilities

Publication date

3 November 2026

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

Details

Jürgen Groß discovered that the Xen network backend driver in the Linux
kernel did not adequately limit the amount of queued packets when a guest
did not process them. An attacker in a guest VM can use this to cause a
denial of service (excessive kernel memory consumption) in the network
backend domain. (CVE-2021-28714)

It was discovered that the Bluetooth subsystem in the Linux kernel
contained a use-after-free vulnerability. A local attacker could use this
to cause a denial of service (system crash) or possibly execute arbitrary
code. (CVE-2021-3640)

Jürgen Groß discovered that the Xen network backend driver in the Linux
kernel did not adequately limit the amount of queued packets when a guest
did not process them. An attacker in a guest VM can use this to cause a
denial of service (excessive kernel memory consumption) in the network
backend domain. (CVE-2021-28714)

It was discovered that the Bluetooth subsystem in the Linux kernel
contained a use-after-free vulnerability. A local attacker could use this
to cause a denial of service (system crash) or possibly execute arbitrary
code. (CVE-2021-3640)

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-4.4.0-1131-fips –  4.4.0-1131.138  
linux-image-4.4.0-1162-kvm –  4.4.0-1162.173  
linux-image-4.4.0-290-generic –  4.4.0-290.324  
linux-image-4.4.0-290-lowlatency –  4.4.0-290.324  
linux-image-fips –  4.4.0.1131.133  
linux-image-generic –  4.4.0.290.296  
linux-image-generic-lts-xenial –  4.4.0.290.296  
linux-image-kvm –  4.4.0.1162.159  
linux-image-lowlatency –  4.4.0.290.296  
linux-image-lowlatency-lts-xenial –  4.4.0.290.296  
linux-image-virtual –  4.4.0.290.296  
linux-image-virtual-lts-xenial –  4.4.0.290.296  
14.04 LTS trusty linux-image-4.4.0-1161-aws –  4.4.0-1161.167  
linux-image-4.4.0-290-generic –  4.4.0-290.324~14.04.1  
linux-image-4.4.0-290-lowlatency –  4.4.0-290.324~14.04.1  
linux-image-aws –  4.4.0.1161.158  
linux-image-generic-lts-xenial –  4.4.0.290.324~14.04.1  
linux-image-lowlatency-lts-xenial –  4.4.0.290.324~14.04.1  
linux-image-virtual-lts-xenial –  4.4.0.290.324~14.04.1  

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References

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