[USN-7854-1] Linux kernel (KVM) vulnerabilities

-----BEGIN PGP SIGNATURE-----

wsB5BAABCAAjFiEEYrygdx1GDec9TV8EZ0GeRcM5nt0FAmkDxrQFAwAAAAAACgkQZ0GeRcM5nt2n
oggArzKql5i5OC/Vse63KXxM8PzW5xcocRGBY93uJH+jxrYieO2YJl/Vbg6Fe/OoIdPmQtqSME/r
IalHq/Fdba45P6wjFNDVWprQ+aoutD+OlkKIehl3mhCqUxwXg0JzWVxVwp1LjHftLjK++Nuv+hXp
BKPFroDYSmndS0d0T9eDSwvl94jJn7Oc23R3LcvE2m/rEKzq71FuZ9nVRFmvkDoK6Caxkrsg7KeV
vSnvPnWndpa4JkyAT7J6hjnhMcQM1iva6XisHnzi+QADDtLOeBfDIwefS80my2jRs1x8FfdayEr5
2krbmT1PyrgmOWw/mjVtSorylwtmP9ztuLEG4Txy0g==
=5fkx
-----END PGP SIGNATURE-----
==========================================================================
Ubuntu Security Notice USN-7854-1
October 30, 2025

linux-kvm vulnerabilities
==========================================================================

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

- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-kvm: Linux kernel for cloud environments

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;
- Framebuffer layer;
- BTRFS file system;
- Ext4 file system;
- Network file system (NFS) server daemon;
- Timer subsystem;
- DCCP (Datagram Congestion Control Protocol);
- IPv6 networking;
- NET/ROM layer;
- Packet sockets;
- Network traffic control;
- SCTP protocol;
- VMware vSockets driver;
- USB sound devices;
(CVE-2023-52574, CVE-2023-52650, CVE-2024-35849, CVE-2024-41006,
CVE-2024-49924, CVE-2024-50006, CVE-2024-50299, CVE-2024-53124,
CVE-2024-53150, CVE-2024-56767, CVE-2025-21796, CVE-2025-37785,
CVE-2025-37838, CVE-2025-38352, CVE-2025-38477, CVE-2025-38617,
CVE-2025-38618)

Update instructions:

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

Ubuntu 18.04 LTS
linux-image-4.15.0-1168-kvm 4.15.0-1168.173
Available with Ubuntu Pro
linux-image-kvm 4.15.0.1168.159
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-7854-1
CVE-2023-52574, CVE-2023-52650, CVE-2024-35849, CVE-2024-41006,
CVE-2024-49924, CVE-2024-50006, CVE-2024-50299, CVE-2024-53124,
CVE-2024-53150, CVE-2024-56767, CVE-2025-21796, CVE-2025-37785,
CVE-2025-37838, CVE-2025-38352, CVE-2025-38477, CVE-2025-38617,
CVE-2025-38618, CVE-2025-40300