CVE-2020-27779

Published: 02 March 2021

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.

From the Ubuntu security team

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.

Priority

Medium

CVSS 3 base score: 7.5

Status

Package Release Status
grub2-signed
Launchpad, Ubuntu, Debian
Upstream Needs triage

Ubuntu 21.04 (Hirsute Hippo)
Released (1.164)
Ubuntu 20.04 LTS (Focal Fossa)
Released (1.167.2)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (1.167~18.04.5)
Ubuntu 16.04 ESM (Xenial Xerus) Pending
(1.164)
Ubuntu 14.04 ESM (Trusty Tahr) Needs triage

grub2-unsigned
Launchpad, Ubuntu, Debian
Upstream Needs triage

Ubuntu 21.04 (Hirsute Hippo)
Released (2.04-1ubuntu42)
Ubuntu 20.04 LTS (Focal Fossa)
Released (2.04-1ubuntu44.2)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (2.04-1ubuntu44.1.2)
Ubuntu 16.04 ESM (Xenial Xerus) Pending
(2.04-1ubuntu42)
Ubuntu 14.04 ESM (Trusty Tahr) Needs triage

Notes

AuthorNote
sbeattie
grub2-unsigned will contain fixes and supersede grub2, which will contain only BIOS grub bits.

References