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Ubuntu 16.04 LTS USN-3836-2 Moderate: Linux Kernel Access Issues

ubuntu
Calendar Grey December 4, 2018
Dist Ubuntu Esm H88
Multiple vulnerabilities in the Linux kernel for Ubuntu 16.04 LTS have been mitigated, enhancing safeguards against unauthorized intrusions.
Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

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

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

Details:

USN-3836-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04

LTS. This update provides the corresponding updates for the Linux

Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu

16.04 LTS.

Jann Horn discovered that the Linux kernel mishandles mapping UID or GID

ranges inside nested user namespaces in some situations. A local attacker

could use this to bypass access controls on resources outside the

namespace. (CVE-2018-18955)

Philipp Wendler discovered that the overlayfs implementation in the Linux

kernel did not properly verify the directory contents permissions from

within a unprivileged user namespace. A local attacker could use this to

expose sensitive information (protected file names). (CVE-2018-6559)

Topics%20covered

Topics Covered

security advisory access control moderate severity update instructions ubuntu linux kernel linux-gcp

Update Instructions

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

Ubuntu 16.04 LTS:
  linux-image-4.15.0-1025-gcp     4.15.0-1025.26~16.04.1
  linux-image-4.15.0-42-generic   4.15.0-42.45~16.04.1
  linux-image-4.15.0-42-generic-lpae  4.15.0-42.45~16.04.1
  linux-image-4.15.0-42-lowlatency  4.15.0-42.45~16.04.1
  linux-image-gcp                 4.15.0.1025.39
  linux-image-generic-hwe-16.04   4.15.0.42.63
  linux-image-generic-lpae-hwe-16.04  4.15.0.42.63
  linux-image-gke                 4.15.0.1025.39
  linux-image-lowlatency-hwe-16.04  4.15.0.42.63
  linux-image-oem                 4.15.0.42.63

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-3836-2

https://ubuntu.com/security/notices/USN-3836-1

CVE-2018-18955, CVE-2018-6559

December 04, 2018

Topics%20covered

Topics Covered

security advisory access control moderate severity update instructions ubuntu linux kernel linux-gcp

Package Information

https://launchpad.net/ubuntu/+source/linux-gcp/4.15.0-1025.26~16.04.1
https://launchpad.net/ubuntu/+source/linux-hwe/4.15.0-42.45~16.04.1

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