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Ubuntu 18.04 LTS: USN-3833-1 High: Linux Kernel Access Control Issues

ubuntu
Calendar Grey November 30, 2018
Dist Ubuntu Esm H88
Numerous security flaws in the Ubuntu 18.04 LTS Linux kernel for AWS have been addressed. Users are urged to apply updates to improve system safety.
Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux-aws: Linux kernel for Amazon Web Services (AWS) systems

Details:

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 high ubuntu overwrite linux kernel aws

Update Instructions

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-1029-aws     4.15.0-1029.30
  linux-image-aws                 4.15.0.1029.29

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-3833-1

CVE-2018-18955, CVE-2018-6559

November 30, 2018

Topics%20covered

Topics Covered

security advisory access control high ubuntu overwrite linux kernel aws

Package Information

https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1029.30

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