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Ubuntu 18.04 LTS Linux Kernel Critical Privilege Escalation USN-8390-1

ubuntu
Calendar Grey June 4, 2026
Dist Ubuntu Esm H88
========================================================================== Ubuntu Security Notice US
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: Linux kernel

- linux-azure-4.15: Linux kernel for Microsoft Azure Cloud systems

- linux-azure-fips: Linux kernel for Microsoft Azure Cloud systems with FIPS

- linux-fips: Linux kernel with FIPS

- linux-gcp-4.15: Linux kernel for Google Cloud Platform (GCP) systems

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

FIPS

- linux-kvm: Linux kernel for cloud environments

- linux-oracle: Linux kernel for Oracle Cloud systems

- linux-azure: Linux kernel for Microsoft Azure 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 critical privilege escalation Ubuntu Linux kernel container escape

Update Instructions

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

Ubuntu 18.04 LTS
   linux-image-4.15.0-1148-fips    4.15.0-1148.160
                                   Available with Ubuntu Pro
   linux-image-4.15.0-1155-oracle  4.15.0-1155.166
                                   Available with Ubuntu Pro
   linux-image-4.15.0-1175-kvm     4.15.0-1175.180
                                   Available with Ubuntu Pro
   linux-image-4.15.0-1186-gcp     4.15.0-1186.203
                                   Available with Ubuntu Pro
   linux-image-4.15.0-1202-azure   4.15.0-1202.217
                                   Available with Ubuntu Pro
   linux-image-4.15.0-2094-gcp-fips  4.15.0-2094.100
                                   Available with Ubuntu Pro
   linux-image-4.15.0-2111-azure-fips  4.15.0-2111.117
                                   Available with Ubuntu Pro
   linux-image-4.15.0-251-generic  4.15.0-251.263
                                   Available with Ubuntu Pro
   linux-image-4.15.0-251-lowlatency  4.15.0-251.263
                                   Available with Ubuntu Pro
   linux-image-azure-4.15          4.15.0.1202.170
                                   Available with Ubuntu Pro
   linux-image-azure-fips          4.15.0.2111.107
                                   Available with Ubuntu Pro
   linux-image-azure-fips-4.15     4.15.0.2111.107
                                   Available with Ubuntu Pro
   linux-image-azure-lts-18.04     4.15.0.1202.170
                                   Available with Ubuntu Pro
   linux-image-fips                4.15.0.1148.145
                                   Available with Ubuntu Pro
   linux-image-gcp-4.15            4.15.0.1186.199
                                   Available with Ubuntu Pro
   linux-image-gcp-fips            4.15.0.2094.92
                                   Available with Ubuntu Pro
   linux-image-gcp-fips-4.15       4.15.0.2094.92
                                   Available with Ubuntu Pro
   linux-image-gcp-lts-18.04       4.15.0.1186.199
                                   Available with Ubuntu Pro
   linux-image-generic             4.15.0.251.235
                                   Available with Ubuntu Pro
   linux-image-kvm                 4.15.0.1175.166
                                   Available with Ubuntu Pro
   linux-image-lowlatency          4.15.0.251.235
                                   Available with Ubuntu Pro
   linux-image-oracle-4.15         4.15.0.1155.160
                                   Available with Ubuntu Pro
   linux-image-oracle-lts-18.04    4.15.0.1155.160
                                   Available with Ubuntu Pro
   linux-image-virtual             4.15.0.251.235
                                   Available with Ubuntu Pro

Ubuntu 14.04 LTS
   linux-image-4.15.0-1202-azure   4.15.0-1202.217~14.04.1
                                   Available with Ubuntu Pro
   linux-image-azure               4.15.0.1202.217~14.04.1
                                   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-8390-1

CVE-2026-43284

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8390-1

Topics%20covered

Topics Covered

security advisory critical privilege escalation Ubuntu Linux kernel container escape

Package Information

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