[USN-7937-1] Linux kernel (Azure FIPS) vulnerabilities

[Rodrigo Figueiredo Zaiden]

==========================================================================
Ubuntu Security Notice USN-7937-1
December 16, 2025

linux-azure-fips 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-azure-fips: Linux kernel for Microsoft Azure Cloud systems with FIPS

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:
   - Cryptographic API;
   - ACPI drivers;
   - DMA engine subsystem;
   - GPU drivers;
   - HSI subsystem;
   - Hardware monitoring drivers;
   - InfiniBand drivers;
   - Mailbox framework;
   - Network drivers;
   - Ethernet team driver;
   - AFS file system;
   - Ceph distributed file system;
   - Ext4 file system;
   - Network file system (NFS) server daemon;
   - NILFS2 file system;
   - File systems infrastructure;
   - KVM subsystem;
   - L3 Master device support module;
   - Timer subsystem;
   - Tracing infrastructure;
   - Memory management;
   - Appletalk network protocol;
   - DCCP (Datagram Congestion Control Protocol);
   - IPv6 networking;
   - Netfilter;
   - NET/ROM layer;
   - Open vSwitch;
   - SCTP protocol;
   - USB sound devices;
(CVE-2021-47385, CVE-2022-49026, CVE-2022-49390, CVE-2023-52574,
CVE-2023-52650, CVE-2024-41006, CVE-2024-49935, CVE-2024-49963,
CVE-2024-50006, CVE-2024-50067, CVE-2024-50095, CVE-2024-50179,
CVE-2024-50299, CVE-2024-53090, CVE-2024-53112, CVE-2024-53124,
CVE-2024-53150, CVE-2024-53217, CVE-2024-56767, CVE-2024-58083,
CVE-2025-21715, CVE-2025-21722, CVE-2025-21761, CVE-2025-21791,
CVE-2025-21811, CVE-2025-21855, CVE-2025-37838, CVE-2025-37958,
CVE-2025-38352, CVE-2025-38666, CVE-2025-39964, CVE-2025-40018)

Update instructions:

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

Ubuntu 18.04 LTS
   linux-image-4.15.0-2104-azure-fips  4.15.0-2104.110
                                   Available with Ubuntu Pro
   linux-image-azure-fips          4.15.0.2104.100
                                   Available with Ubuntu Pro
   linux-image-azure-fips-4.15     4.15.0.2104.100
                                   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-7937-1
   CVE-2021-47385, CVE-2022-49026, CVE-2022-49390, CVE-2023-52574,
   CVE-2023-52650, CVE-2024-41006, CVE-2024-49935, CVE-2024-49963,
   CVE-2024-50006, CVE-2024-50067, CVE-2024-50095, CVE-2024-50179,
   CVE-2024-50299, CVE-2024-53090, CVE-2024-53112, CVE-2024-53124,
   CVE-2024-53150, CVE-2024-53217, CVE-2024-56767, CVE-2024-58083,
   CVE-2025-21715, CVE-2025-21722, CVE-2025-21761, CVE-2025-21791,
   CVE-2025-21811, CVE-2025-21855, CVE-2025-37838, CVE-2025-37958,
   CVE-2025-38352, CVE-2025-38666, CVE-2025-39964, CVE-2025-40018,
   CVE-2025-40300

Package Information:
   https://launchpad.net/ubuntu/+source/linux-azure-fips/4.15.0-2104.110

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