CVE-2021-20225

Publication date 2 March 2021

Last updated 24 July 2024

Ubuntu priority

Cvss 3 Severity Score

A flaw was found in grub2 in versions prior to 2.06. The option parser allows an attacker to write past the end of a heap-allocated buffer by calling certain commands with a large number of specific short forms of options. 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 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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
grub2	24.10 oracular	Not affected
	24.04 LTS noble	Not affected
	23.10 mantic	Not affected
	23.04 lunar	Not affected
	22.10 kinetic	Not affected
	22.04 LTS jammy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected
grub2-signed	24.10 oracular	Not affected
	24.04 LTS noble	Not affected
	23.10 mantic	Not affected
	23.04 lunar	Not affected
	22.10 kinetic	Not affected
	22.04 LTS jammy	Not affected
	21.10 impish	Fixed 1.169
	21.04 hirsute	Fixed 1.164
	20.10 groovy	Fixed 1.167.2
	20.04 LTS focal	Fixed 1.167.2
	18.04 LTS bionic	Fixed 1.167~18.04.5
	16.04 LTS xenial	Fixed 1.164
	14.04 LTS trusty	Ignored end of ESM support, was needed
grub2-unsigned	24.10 oracular	Not affected
	24.04 LTS noble	Not affected
	23.10 mantic	Not affected
	23.04 lunar	Not affected
	22.10 kinetic	Not affected
	22.04 LTS jammy	Not affected
	21.10 impish	Fixed 2.04-1ubuntu45
	21.04 hirsute	Fixed 2.04-1ubuntu42
	20.10 groovy	Fixed 2.04-1ubuntu44.2
	20.04 LTS focal	Fixed 2.04-1ubuntu44.2
	18.04 LTS bionic	Fixed 2.04-1ubuntu44.1.2
	16.04 LTS xenial	Fixed 2.04-1ubuntu42
	14.04 LTS trusty	Not in release

Notes

sbeattie

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

Severity score breakdown

Parameter	Value
Base score	6.7 · Medium
Attack vector	Local
Attack complexity	Low
Privileges required	High
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H