Affected: grub2

A flaw was found in grub2 in versions prior to 2.06. The cutmem command does not honor secure boot locking allowing an privileged attacker to remove address ranges from memory creating an opportunity to circumvent SecureBoot protections after proper triage about grub's memory layout. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Affected: Ubuntu:18.04:LTS: grub2-signed, Ubuntu:18.04:LTS: grub2-unsigned, Ubuntu:20.04:LTS: grub2-signed, Ubuntu:20.04:LTS: grub2-unsigned

Máté Kukri discovered that the acpi command in GRUB 2 allowed privileged users to load crafted ACPI tables when secure boot is enabled. An attacker could use this to bypass UEFI Secure Boot restrictions. (CVE-2020-14372)

Chris Coulson discovered that the rmmod command in GRUB 2 contained a use- after-free vulnerability. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-25632)

Chris Coulson discovered that a buffer overflow existed in the command line parser in GRUB 2. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-27749)

It was discovered that the cutmem command in GRUB 2 did not honor secure boot locking. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-27779)

It was discovered that the option parser in GRUB 2 contained a heap overflow vulnerability. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2021-20225)

It was discovered that the menu rendering implementation in GRUB 2 did not properly calculate the amount of memory needed in some situations, leading to out-of-bounds writes. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2021-20233)