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CVE-2020-15705

Published: 29 July 2020

GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This only affects systems where the kernel signing certificate has been imported directly into the secure boot database and the GRUB image is booted directly without the use of shim. This issue affects GRUB2 version 2.04 and prior versions.

From the Ubuntu Security Team

Mathieu Trudel-Lapierre discovered that in certain situations, GRUB2 failed to validate kernel signatures. A local attacker could use this to bypass Secure Boot restrictions.

Notes

AuthorNote
alexmurray
grub2-signed is not supported in Ubuntu 12.04 ESM (precise/esm) and so marking the priority for grub2 in this release as low

Priority

Medium

Cvss 3 Severity Score

6.4

Score breakdown

Status

Package Release Status
grub2
Launchpad, Ubuntu, Debian
upstream Needs triage

trusty
Released (2.02~beta2-9ubuntu1.20)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
xenial
Released (2.02~beta2-36ubuntu3.26)
bionic
Released (2.02-2ubuntu8.16)
focal
Released (2.04-1ubuntu26.1)
jammy Not vulnerable
(2.06-2ubuntu7)
kinetic Not vulnerable
(2.06-2ubuntu12)
lunar Not vulnerable
(2.06-2ubuntu16)
hirsute Not vulnerable
(2.04-1ubuntu26.1)
groovy Not vulnerable
(2.04-1ubuntu26.1)
grub2-signed
Launchpad, Ubuntu, Debian
upstream Needs triage

trusty
Released (1.34.22)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
xenial
Released (1.66.26)
bionic
Released (1.93.18)
eoan Ignored
(end of life)
jammy Not vulnerable
(1.180)
kinetic Not vulnerable
(1.185)
lunar Not vulnerable
(1.192)
hirsute Not vulnerable
(1.147)
focal
Released (1.142.3)
groovy Not vulnerable
(1.147)
grub2-unsigned
Launchpad, Ubuntu, Debian
trusty Does not exist

xenial Needed

bionic Not vulnerable
(2.04-1ubuntu47.4)
focal Not vulnerable
(2.04-1ubuntu47.4)
jammy Not vulnerable
(2.06-2ubuntu10)
kinetic Not vulnerable
(2.06-2ubuntu12)
lunar Not vulnerable
(2.06-2ubuntu16)
upstream Needs triage

Severity score breakdown

Parameter Value
Base score 6.4
Attack vector Local
Attack complexity High
Privileges required High
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H