Integer overflows were discovered in the functions grub_cmd_initrd and grub_initrd_init in the efilinux component of GRUB2, as shipped in Debian, Red Hat, and Ubuntu (the functionality is not included in GRUB2 upstream), leading to a heap-based buffer overflow. These could be triggered by an extremely large number of arguments to the initrd command on 32-bit architectures, or a crafted filesystem with very large files on any architecture. An attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. This issue affects GRUB2 version 2.04 and prior versions.
https://www.suse.com/support/kb/doc/?id=000019673
http://ubuntu.com/security/notices/USN-4432-1
https://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html
https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass
https://www.debian.org/security/2020-GRUB-UEFI-SecureBoot
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011
https://access.redhat.com/security/vulnerabilities/grub2bootloader
https://www.eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/
https://www.suse.com/c/suse-addresses-grub2-secure-boot-issue/
https://www.openwall.com/lists/oss-security/2020/07/29/3
https://www.debian.org/security/2020/dsa-4735
http://www.openwall.com/lists/oss-security/2020/07/29/3
https://security.netapp.com/advisory/ntap-20200731-0008/
https://usn.ubuntu.com/4432-1/
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00017.html
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00016.html
Source: MITRE
Published: 2020-07-29
Updated: 2021-09-13
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