[USN-8255-2] Linux kernel (Azure) vulnerabilities

========================================================================== Ubuntu Security Notice USN-8255-2 May 11, 2026 linux-azure-5.15 vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 20.04 LTS Summary: Several security issues were fixed in the Linux kernel. Software Description: - linux-azure-5.15: Linux kernel for Microsoft Azure cloud systems Details: Stonejiajia, Shir Tamari and Sagi Tzadik discovered that the OverlayFS implementation in the Ubuntu Linux kernel did not properly perform permission checks in certain situations. A local attacker could possibly use this to gain elevated privileges. (CVE-2023-2640) Shir Tamari and Sagi Tzadik discovered that the OverlayFS implementation in the Ubuntu Linux kernel did not properly perform permission checks in certain situations. A local attacker could possibly use this to gain elevated privileges. (CVE-2023-32629) 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: - Network drivers; - NVME drivers; (CVE-2026-23112, CVE-2026-23273) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 20.04 LTS linux-image-5.15.0-1111-azure 5.15.0-1111.120~20.04.1 Available with Ubuntu Pro linux-image-azure 5.15.0.1111.120~20.04.1 Available with Ubuntu Pro linux-image-azure-5.15 5.15.0.1111.120~20.04.1 Available with Ubuntu Pro linux-image-azure-cvm 5.15.0.1111.120~20.04.1 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-8255-2 https://ubuntu.com/security/notices/USN-8255-1 CVE-2023-2640, CVE-2023-32629, CVE-2026-23112, CVE-2026-23273