[USN-8666-2] Linux kernel (Azure) vulnerabilities

[Rodrigo Figueiredo Zaiden]

==========================================================================
Ubuntu Security Notice USN-8666-2
August 25, 2026

linux-azure-5.4, linux-azure-fips vulnerabilities
==========================================================================

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

- Ubuntu 20.04 LTS
- 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
- linux-azure-5.4: Linux kernel for Microsoft Azure cloud systems

Details:

Siebe Devroe, Héloïse Gollier, and Mathy Vanhoef discovered that the WiFi
implementation in the Linux kernel did not properly handle aggregated
frames in mesh networks, due to an incorrect fix for CVE-2020-24588. A
physically proximate attacker could use this issue to inject packets.
(CVE-2025-27558)

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:
   - x86 architecture;
   - Cryptographic API;
   - InfiniBand drivers;
   - Media drivers;
   - NVIDIA Tegra memory controller driver;
   - Network drivers;
   - NVME drivers;
   - File systems infrastructure;
   - Ext4 file system;
   - IPv4 networking;
   - Network traffic control;
   - TCP network protocol;
   - Locking primitives;
   - B.A.T.M.A.N. meshing protocol;
   - Ceph Core library;
   - IPv6 networking;
   - Multipath TCP;
   - Netfilter;
   - SCTP protocol;
   - SMC sockets;
   - TIPC protocol;
(CVE-2021-47378, CVE-2026-23392, CVE-2026-31405, CVE-2026-31414,
CVE-2026-31448, CVE-2026-31657, CVE-2026-31668, CVE-2026-43071,
CVE-2026-43198, CVE-2026-43493, CVE-2026-43499, CVE-2026-46266,
CVE-2026-46331, CVE-2026-52914, CVE-2026-52924, CVE-2026-52931,
CVE-2026-52955, CVE-2026-52958, CVE-2026-52982, CVE-2026-52986,
CVE-2026-52989, CVE-2026-52993, CVE-2026-52999, CVE-2026-53002,
CVE-2026-53006, CVE-2026-53045, CVE-2026-53088, CVE-2026-53176,
CVE-2026-53212, CVE-2026-53228, CVE-2026-53359)

Update instructions:

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

Ubuntu 20.04 LTS
   linux-image-5.4.0-1167-azure-fips  5.4.0-1167.173+fips1
                                   Available with Ubuntu Pro
   linux-image-azure-fips          5.4.0.1167.103
                                   Available with Ubuntu Pro
   linux-image-azure-fips-5.4      5.4.0.1167.103
                                   Available with Ubuntu Pro

Ubuntu 18.04 LTS
   linux-image-5.4.0-1167-azure    5.4.0-1167.173~18.04.1
                                   Available with Ubuntu Pro
   linux-image-azure               5.4.0.1167.173~18.04.1
                                   Available with Ubuntu Pro
   linux-image-azure-5.4           5.4.0.1167.173~18.04.1
                                   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-8666-2
   https://ubuntu.com/security/notices/USN-8666-1
   CVE-2021-47378, CVE-2025-27558, CVE-2026-23392, CVE-2026-31405,
   CVE-2026-31414, CVE-2026-31448, CVE-2026-31657, CVE-2026-31668,
   CVE-2026-43071, CVE-2026-43198, CVE-2026-43493, CVE-2026-43499,
   CVE-2026-46266, CVE-2026-46331, CVE-2026-52914, CVE-2026-52924,
   CVE-2026-52931, CVE-2026-52955, CVE-2026-52958, CVE-2026-52982,
   CVE-2026-52986, CVE-2026-52989, CVE-2026-52993, CVE-2026-52999,
   CVE-2026-53002, CVE-2026-53006, CVE-2026-53045, CVE-2026-53088,
   CVE-2026-53176, CVE-2026-53212, CVE-2026-53228, CVE-2026-53359

Package Information:
   https://launchpad.net/ubuntu/+source/linux-azure-fips/5.4.0-1167.173+fips1

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