CVE-2020-15705 GRUB2: avoid loading unsigned kernels when GRUB is booted directly under secureboot without shim

Medium 6.4 Published 29 Jul 2020 Updated 17 Sep 2024

Attackers can bypass Secure Boot to load unsigned kernels when GRUB is booted directly without shim in specific configurations.

Exploited in the wild: Not known
Login needed: An administrator
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2020-15705?

CVE-2020-15705 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 29 Jul 2020. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This only affects systems where the kernel signing certificate has been imported directly into the secure boot database and the GRUB image is booted directly without the use of shim. This issue affects GRUB2 version 2.04 and prior versions.

Weakness: CWE-347

Which versions are affected by CVE-2020-15705?

It affects 14 products.

Linux distribution packages (28)

`grub2` SUSE:Enterprise Storage 5	All versions	`2.02-4.61.1`
`grub2` SUSE:HPE Helion OpenStack 8	All versions	`2.02-4.61.1`
`grub2` SUSE:Linux Enterprise High Performance Computing 15-ESPOS	All versions	`2.02-19.56.1`
`grub2` SUSE:Linux Enterprise High Performance Computing 15-LTSS	All versions	`2.02-19.56.1`
`grub2` SUSE:Linux Enterprise Module for Basesystem 15 SP1	All versions	`2.02-26.33.1`
`grub2` SUSE:Linux Enterprise Module for Basesystem 15 SP2	All versions	`2.04-9.15.1`
`grub2` SUSE:Linux Enterprise Module for Server Applications 15 SP1	All versions	`2.02-26.33.1`
`grub2` SUSE:Linux Enterprise Module for Server Applications 15 SP2	All versions	`2.04-9.15.1`
`grub2` SUSE:Linux Enterprise Server 11 SP4-LTSS	All versions	`2.00-0.66.21.1`
`grub2` SUSE:Linux Enterprise Server 12 SP2-BCL	All versions	`2.02~beta2-115.56.1`
`grub2` SUSE:Linux Enterprise Server 12 SP2-LTSS	All versions	`2.02~beta2-115.56.1`
`grub2` SUSE:Linux Enterprise Server 12 SP3-BCL	All versions	`2.02-4.61.1`
`grub2` SUSE:Linux Enterprise Server 12 SP3-LTSS	All versions	`2.02-4.61.1`
`grub2` SUSE:Linux Enterprise Server 12 SP4-LTSS	All versions	`2.02-12.39.1`
`grub2` SUSE:Linux Enterprise Server 12 SP5	All versions	`2.02-12.39.1`
`grub2` SUSE:Linux Enterprise Server 15-LTSS	All versions	`2.02-19.56.1`
`grub2` SUSE:Linux Enterprise Server for SAP Applications 12 SP2	All versions	`2.02~beta2-115.56.1`
`grub2` SUSE:Linux Enterprise Server for SAP Applications 12 SP3	All versions	`2.02-4.61.1`
`grub2` SUSE:Linux Enterprise Server for SAP Applications 12 SP4	All versions	`2.02-12.39.1`
`grub2` SUSE:Linux Enterprise Server for SAP Applications 12 SP5	All versions	`2.02-12.39.1`
`grub2` SUSE:Linux Enterprise Server for SAP Applications 15	All versions	`2.02-19.56.1`
`grub2` SUSE:OpenStack Cloud 7	All versions	`2.02~beta2-115.56.1`
`grub2` SUSE:OpenStack Cloud 8	All versions	`2.02-4.61.1`
`grub2` SUSE:OpenStack Cloud 9	All versions	`2.02-12.39.1`
`grub2` SUSE:OpenStack Cloud Crowbar 8	All versions	`2.02-4.61.1`
`grub2` SUSE:OpenStack Cloud Crowbar 9	All versions	`2.02-12.39.1`
`grub2` openSUSE:Leap 15.1	All versions	`2.02-lp151.21.27.1`
`grub2` openSUSE:Leap 15.2	All versions	`2.04-lp152.7.9.1`

Products include Canonical Ubuntu Linux, Debian Debian Linux, Gnu Grub2, Microsoft Windows 10, Microsoft Windows 8.1, Microsoft Windows Rt 8.1 and 8 more.

How do I fix CVE-2020-15705?

Apply the vendor's patch.

Is CVE-2020-15705 being exploited?

There is no known exploitation of CVE-2020-15705 in the wild and no public exploit code.

All Canonical Ubuntu Linux vulnerabilities

Sources

Also known as ALPINE-CVE-2020-15705, GHSA-w739-fjv8-98pq, SUSE-SU-2020:14461-1, SUSE-SU-2020:2303-1, SUSE-SU-2020:2304-1, SUSE-SU-2020:2305-1 and 6 more.