Ubuntu Security Notice USN-4911-1
April 13, 2021
A security issue affects these releases of Ubuntu and its derivatives:
– Ubuntu 20.04 LTS
Several security issues were fixed in the Linux kernel.
– linux-oem-5.10: Linux kernel for OEM systems
It was discovered that the Nouveau GPU driver in the Linux kernel did not
properly handle error conditions in some situations. A local attacker could
use this to cause a denial of service (system crash). (CVE-2020-25639)
Jan Beulich discovered that the Xen netback backend in the Linux kernel did
not properly handle certain error conditions under paravirtualization. An
attacker in a guest VM could possibly use this to cause a denial of service
(host domain crash). (CVE-2021-28038)
It was discovered that the fastrpc driver in the Linux kernel did not
prevent user space applications from sending kernel RPC messages. A local
attacker could possibly use this to gain elevated privileges.
It was discovered that the fuse user space file system implementation in
the Linux kernel did not properly handle bad inodes in some situations. A
local attacker could possibly use this to cause a denial of service.
The problem can be corrected by updating your system to the following
Ubuntu 20.04 LTS:
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.
CVE-2020-25639, CVE-2021-28038, CVE-2021-28375, CVE-2021-28950