GRUB2: avoid loading unsigned kernels when GRUB is booted directly under secureboot without shim
CVE-2020-15705

6.4MEDIUM

Key Information:

Vendor

Ubuntu

Status
Grub2 In Ubuntu
Vendor
CVE Published:
29 July 2020

What is CVE-2020-15705?

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.

Affected Version(s)

grub2 in Ubuntu 20.04 LTS < 2.04-1ubuntu26.1

grub2 in Ubuntu 18.04 LTS < 2.02-2ubuntu8.16

grub2 in Ubuntu 16.04 LTS < 2.02~beta2-36ubuntu3.26

References

https://www.eclypsium.com/2020/07/29/theres-a-hole-in-the...
x_refsource_CONFIRM
https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2S...
vendor-advisoryx_refsource_UBUNTU
http://ubuntu.com/security/notices/USN-4432-1
vendor-advisoryx_refsource_UBUNTU

CVSS V3.1

Score:
6.4
Severity:
MEDIUM
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
High
Privileges Required:
High
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Mathieu Trudel-Lapierre
.