ESB-2026.4980

=========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2026.4980 USN-8255-2: Linux kernel (Azure) vulnerabilities 12 May 2026 =========================================================================== AUSCERT Security Bulletin Summary --------------------------------- Product: Linux kernel (Azure) Publisher: Ubuntu Operating System: Ubuntu Resolution: Patch/Upgrade CVE Names: CVE-2026-23273 CVE-2023-32629 CVE-2023-2640 CVE-2026-23112 Original Bulletin: https://ubuntu.com/security/notices/USN-8255-2 Comment: CVSS (Max): 9.8 CVE-2026-23112 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) CVSS Source: Ubuntu Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H EPSS (Max): 91.4% (99th) CVE-2023-2640 2026-05-11 - --------------------------BEGIN INCLUDED TEXT-------------------- USN-8255-2: Linux kernel (Azure) vulnerabilities Publication date 11 May 2026 Overview Several security issues were fixed in the Linux kernel. Releases 20.04 LTS --------------------------------------------------------------------------------- Open side navigation Packages o 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: o Network drivers; o NVME drivers Update instructions 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. The problem can be corrected by updating your system to the following package versions: Ubuntu Package Version Release linux-image-5.15.0-1111-azure - 5.15.0-1111.120~20.04.1 Ubuntu Pro Fix available with Ubuntu Pro . linux-image-azure - 5.15.0.1111.120~20.04.1 Ubuntu Pro Fix available 20.04 LTS with Ubuntu Pro . focal linux-image-azure-5.15 - 5.15.0.1111.120~20.04.1 Ubuntu Pro Fix available with Ubuntu Pro . linux-image-azure-cvm - 5.15.0.1111.120~20.04.1 Ubuntu Pro Fix available with Ubuntu Pro . --------------------------------------------------------------------------------- References o CVE-2026-23273 o CVE-2026-23112 o CVE-2023-32629 o CVE-2023-2640 Related notices o USN-8261-1 o USN-8260-1 o USN-8258-1 o USN-8257-1 o USN-8255-1 o USN-8254-1 o USN-8254-2 o USN-8245-1 o USN-8244-1 o USN-6285-1 o USN-6261-1 o USN-6260-1 o USN-6251-1 o USN-6250-1 o USN-6248-1 o LSN-0097-1 --------------------------------------------------------------------------------- - --------------------------END INCLUDED TEXT---------------------- You have received this e-mail bulletin as a result of your organisation's registration with AUSCERT. 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