1. Ubuntu Security Notices
  2. USN-8617-1

USN-8617-1: Linux kernel (KVM) vulnerabilities

Publication date

28 July 2026

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • linux-kvm - Linux kernel for cloud environments

Details

It was discovered that a logic flaw existed in the XFRM ESP-in-TCP
subsystem in the Linux kernel when handling socket buffer fragments. This
flaw is known as Fragnesia. A local attacker could use this to escalate
privileges, or possibly escape a container. (CVE-2026-43503)

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:

  • InfiniBand drivers;
  • STMicroelectronics network drivers;
  • SCSI subsystem;
  • USB over IP driver;
  • SMB network file system;
  • Tracing infrastructure;
  • B.A.T.M.A.N. meshing protocol;
  • Ethernet bridge;
  • Ceph Core library;
  • IPv4 networking;
  • IPv6 networking;
  • Netfilter;
  • RxRPC session sockets;
  • X.25 network layer

It was discovered that a logic flaw existed in the XFRM ESP-in-TCP
subsystem in the Linux kernel when handling socket buffer fragments. This
flaw is known as Fragnesia. A local attacker could use this to escalate
privileges, or possibly escape a container. (CVE-2026-43503)

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:

  • InfiniBand drivers;
  • STMicroelectronics network drivers;
  • SCSI subsystem;
  • USB over IP driver;
  • SMB network file system;
  • Tracing infrastructure;
  • B.A.T.M.A.N. meshing protocol;
  • Ethernet bridge;
  • Ceph Core library;
  • IPv4 networking;
  • IPv6 networking;
  • Netfilter;
  • RxRPC session sockets;
  • X.25 network layer

Update instructions

After a standard system update you need to reboot your computer to make all the necessary changes.

Learn more about how to get the fixes.

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 Release Package Version
20.04 LTS focal linux-image-5.4.0-1148-kvm –  5.4.0-1148.157  
linux-image-kvm –  5.4.0.1148.144  
linux-image-kvm-5.4 –  5.4.0.1148.144  

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References

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