[USN-7863-1] Linux kernel vulnerabilities

[Rodrigo Figueiredo Zaiden]

==========================================================================
Ubuntu Security Notice USN-7863-1
November 06, 2025

linux, linux-aws, linux-kvm, linux-lts-xenial vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- 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;
(CVE-2021-47294, CVE-2021-47330, CVE-2023-52574, CVE-2023-52650,
CVE-2024-50006, CVE-2024-50299, CVE-2024-53124, CVE-2024-53150,
CVE-2024-56767, CVE-2025-37838, CVE-2025-38352)

Update instructions:

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

Ubuntu 16.04 LTS
   linux-image-4.4.0-1150-kvm      4.4.0-1150.161
                                   Available with Ubuntu Pro
   linux-image-4.4.0-1187-aws      4.4.0-1187.202
                                   Available with Ubuntu Pro
   linux-image-4.4.0-274-generic   4.4.0-274.308
                                   Available with Ubuntu Pro
   linux-image-4.4.0-274-lowlatency  4.4.0-274.308
                                   Available with Ubuntu Pro
   linux-image-aws                 4.4.0.1187.191
                                   Available with Ubuntu Pro
   linux-image-generic             4.4.0.274.280
                                   Available with Ubuntu Pro
   linux-image-generic-lts-xenial  4.4.0.274.280
                                   Available with Ubuntu Pro
   linux-image-kvm                 4.4.0.1150.147
                                   Available with Ubuntu Pro
   linux-image-lowlatency          4.4.0.274.280
                                   Available with Ubuntu Pro
   linux-image-lowlatency-lts-xenial  4.4.0.274.280
                                   Available with Ubuntu Pro
   linux-image-virtual             4.4.0.274.280
                                   Available with Ubuntu Pro
   linux-image-virtual-lts-xenial  4.4.0.274.280
                                   Available with Ubuntu Pro

Ubuntu 14.04 LTS
   linux-image-4.4.0-1149-aws      4.4.0-1149.155
                                   Available with Ubuntu Pro
   linux-image-4.4.0-274-generic   4.4.0-274.308~14.04.1
                                   Available with Ubuntu Pro
   linux-image-4.4.0-274-lowlatency  4.4.0-274.308~14.04.1
                                   Available with Ubuntu Pro
   linux-image-aws                 4.4.0.1149.146
                                   Available with Ubuntu Pro
   linux-image-generic-lts-xenial  4.4.0.274.308~14.04.1
                                   Available with Ubuntu Pro
   linux-image-lowlatency-lts-xenial  4.4.0.274.308~14.04.1
                                   Available with Ubuntu Pro
   linux-image-virtual-lts-xenial  4.4.0.274.308~14.04.1
                                   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-7863-1
   CVE-2021-47294, CVE-2021-47330, CVE-2023-52574, CVE-2023-52650,
   CVE-2024-50006, CVE-2024-50299, CVE-2024-53124, CVE-2024-53150,
   CVE-2024-56767, CVE-2025-37838, CVE-2025-38352, CVE-2025-40300

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