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Ubuntu 16.04 LTS Important Linux Kernel Local Escalation USN-8390-2

ubuntu
Calendar Grey June 17, 2026
Scroller Ubuntu Esm H88
Ubuntu 16.04 LTS has a critical issue allowing local programs to gain administrative access through socket operations.
The system could be made to run programs as an administrator.

Summary

The system could be made to run programs as an administrator.

Software Description:

- linux-azure: Linux kernel for Microsoft Azure Cloud systems

- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

- linux-hwe: Linux hardware enablement (HWE) kernel

- linux-oracle: Linux kernel for Oracle Cloud systems

Details:

It was discovered that the Linux kernel did not properly handle shared page

fragments during socket buffer operations, collectively known as Dirty

Frag. A logic flaw existed in the XFRM ESP-in-TCP subsystem and in the

RxRPC networking subsystem when processing paged fragments. A local

attacker could use this to escalate privileges, or possibly escape a

container.

Topics%20covered

Topics Covered

security advisory local privilege escalation Ubuntu important Linux kernel socket operation

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 16.04 LTS
   linux-image-4.15.0-1155-oracle  4.15.0-1155.166~16.04.1
                                   Available with Ubuntu Pro
   linux-image-4.15.0-1186-gcp     4.15.0-1186.203~16.04.1
                                   Available with Ubuntu Pro
   linux-image-4.15.0-1202-azure   4.15.0-1202.217~16.04.1
                                   Available with Ubuntu Pro
   linux-image-4.15.0-251-generic  4.15.0-251.263~16.04.1
                                   Available with Ubuntu Pro
   linux-image-4.15.0-251-lowlatency  4.15.0-251.263~16.04.1
                                   Available with Ubuntu Pro
   linux-image-azure               4.15.0.1202.217~16.04.1
                                   Available with Ubuntu Pro
   linux-image-gcp                 4.15.0.1186.203~16.04.1
                                   Available with Ubuntu Pro
   linux-image-generic-hwe-16.04   4.15.0.251.263~16.04.1
                                   Available with Ubuntu Pro
   linux-image-gke                 4.15.0.1186.203~16.04.1
                                   Available with Ubuntu Pro
   linux-image-lowlatency-hwe-16.04  4.15.0.251.263~16.04.1
                                   Available with Ubuntu Pro
   linux-image-oem                 4.15.0.251.263~16.04.1
                                   Available with Ubuntu Pro
   linux-image-oracle              4.15.0.1155.166~16.04.1
                                   Available with Ubuntu Pro
   linux-image-virtual-hwe-16.04   4.15.0.251.263~16.04.1
                                   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-8390-2

https://ubuntu.com/security/notices/USN-8390-1

CVE-2026-43284

Severity
important
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8390-2

Topics%20covered

Topics Covered

security advisory local privilege escalation Ubuntu important Linux kernel socket operation

Package Information

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