MEDIUM
GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions.
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00016.html
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00017.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/dsa-4735
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: 2020-08-08
Type: CWE-362
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