USN-5050-1: Linux kernel vulnerabilities

24 August 2021

Several security issues were fixed in the Linux kernel.

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Releases

Packages

Details

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly perform access control. An authenticated attacker could possibly
use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Michael Brown discovered that the Xen netback driver in the Linux kernel
did not properly handle malformed packets from a network PV frontend,
leading to a use-after-free vulnerability. An attacker in a guest VM could
use this to cause a denial of service or possibly execute arbitrary code.
(CVE-2021-28691)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly handle HCI device initialization failure, leading to a double-free
vulnerability. An attacker could use this to cause a denial of service or
possibly execute arbitrary code. (CVE-2021-3564)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly handle HCI device detach events, leading to a use-after-free
vulnerability. An attacker could use this to cause a denial of service or
possibly execute arbitrary code. (CVE-2021-3573)

It was discovered that the NFC implementation in the Linux kernel did not
properly handle failed connect events leading to a NULL pointer
dereference. A local attacker could use this to cause a denial of service.
(CVE-2021-38208)

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Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

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Update instructions

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

Ubuntu 20.04

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

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