========================================================================== Ubuntu Security Notice USN-7874-3 December 04, 2025 linux-iot 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-iot: Linux kernel for IoT platforms 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: - HSI subsystem; - I3C subsystem; - SMB network file system; - Padata parallel execution mechanism; - Timer subsystem; - Networking core; (CVE-2023-52854, CVE-2024-35867, CVE-2024-50061, CVE-2024-56664, CVE-2025-21727, CVE-2025-37838, CVE-2025-38352) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 20.04 LTS linux-image-5.4.0-1056-iot 5.4.0-1056.59 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-7874-3 https://ubuntu.com/security/notices/USN-7874-2 https://ubuntu.com/security/notices/USN-7874-1 CVE-2023-52854, CVE-2024-35867, CVE-2024-50061, CVE-2024-56664, CVE-2025-21727, CVE-2025-37838, CVE-2025-38352, CVE-2025-40300
