1. Ubuntu Security Notices
  2. USN-8548-1

USN-8548-1: Linux kernel vulnerabilities

Publication date

15 July 2026

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-fips - Linux kernel with FIPS
  • linux-lts-xenial - Linux hardware enablement kernel from Xenial for Trusty

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:

  • SCSI subsystem;
  • Thermal drivers;
  • USB over IP driver;
  • File systems infrastructure;
  • Ext4 file system;
  • Network file system (NFS) server daemon;
  • SMB network file system;
  • Tracing infrastructure;
  • B.A.T.M.A.N. meshing protocol;
  • Ceph Core library;
  • DCCP (Datagram Congestion Control Protocol);
  • IPv4 networking;
  • IPv6...

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:

  • SCSI subsystem;
  • Thermal drivers;
  • USB over IP driver;
  • File systems infrastructure;
  • Ext4 file system;
  • Network file system (NFS) server daemon;
  • SMB network file system;
  • Tracing infrastructure;
  • B.A.T.M.A.N. meshing protocol;
  • Ceph Core library;
  • DCCP (Datagram Congestion Control Protocol);
  • 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
16.04 LTS xenial linux-image-4.4.0-1126-fips –  4.4.0-1126.133  
linux-image-fips –  4.4.0.1126.128  
14.04 LTS trusty linux-image-4.4.0-1156-aws –  4.4.0-1156.162  
linux-image-4.4.0-283-generic –  4.4.0-283.317~14.04.1  
linux-image-4.4.0-283-lowlatency –  4.4.0-283.317~14.04.1  
linux-image-aws –  4.4.0.1156.153  
linux-image-generic-lts-xenial –  4.4.0.283.317~14.04.1  
linux-image-lowlatency-lts-xenial –  4.4.0.283.317~14.04.1  
linux-image-virtual-lts-xenial –  4.4.0.283.317~14.04.1  

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References

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