MEDIUM
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.
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00067.html
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00069.html
http://ubuntu.com/security/notices/USN-4432-1
http://www.openwall.com/lists/oss-security/2020/07/29/3
https://access.redhat.com/security/vulnerabilities/grub2bootloader
https://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011
https://security.netapp.com/advisory/ntap-20200731-0008/
https://usn.ubuntu.com/4432-1/
https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass
https://www.debian.org/security/2020-GRUB-UEFI-SecureBoot
https://www.eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/
https://www.openwall.com/lists/oss-security/2020/07/29/3
https://www.suse.com/c/suse-addresses-grub2-secure-boot-issue/
Source: MITRE
Published: 2020-07-29
Updated: 2020-08-29
Type: CWE-347
Base Score: 4.4
Vector: AV:L/AC:M/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 3.4
Severity: MEDIUM
Base Score: 6.4
Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 0.5
Severity: MEDIUM