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CVE-2020-25632

Published: 2 March 2021

A flaw was found in grub2 in versions prior to 2.06. The rmmod implementation allows the unloading of a module used as a dependency without checking if any other dependent module is still loaded leading to a use-after-free scenario. This could allow arbitrary code to be executed or a bypass of Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

From the Ubuntu Security Team

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.

Notes

AuthorNote
alexmurray
CVE title: "grub2: use-after-free in rmmod command"
sbeattie
grub2-unsigned will contain fixes and supersede grub2, which will contain only BIOS grub bits.

Priority

Medium

Cvss 3 Severity Score

7.5

Score breakdown

Status

Package Release Status
grub2-signed
Launchpad, Ubuntu, Debian
bionic
Released (1.167~18.04.5)
focal
Released (1.167.2)
groovy
Released (1.167.2)
hirsute
Released (1.164)
impish
Released (1.169)
jammy
Released (1.169)
kinetic
Released (1.169)
precise Does not exist

trusty Needs triage

upstream Needs triage

xenial Pending
(1.164)
grub2-unsigned
Launchpad, Ubuntu, Debian
bionic
Released (2.04-1ubuntu44.1.2)
focal
Released (2.04-1ubuntu44.2)
groovy
Released (2.04-1ubuntu44.2)
hirsute
Released (2.04-1ubuntu42)
impish
Released (2.04-1ubuntu45)
jammy
Released (2.04-1ubuntu45)
kinetic
Released (2.04-1ubuntu45)
precise Ignored
(end of ESM support, was needs-triage)
trusty Needs triage

upstream Needs triage

xenial Pending
(2.04-1ubuntu42)

Severity score breakdown

Parameter Value
Base score 7.5
Attack vector Local
Attack complexity High
Privileges required High
User interaction None
Scope Changed
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H