CVE-2020-15706

Publication date 29 July 2020

Last updated 24 July 2024

Ubuntu priority

High

Why this priority?

Cvss 3 Severity Score

6.4 · Medium

Score breakdown

GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions.

From the Ubuntu Security Team

Chris Coulson discovered that the GRUB2 function handling code did not properly handle a function being redefined, leading to a use-after-free 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

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
21.04 hirsute
Not affected
20.10 groovy
Not affected
20.04 LTS focal
Fixed 2.04-1ubuntu26.1
18.04 LTS bionic
Fixed 2.02-2ubuntu8.16
16.04 LTS xenial
Fixed 2.02~beta2-36ubuntu3.26
14.04 LTS trusty
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
21.04 hirsute
Not affected
20.10 groovy
Not affected
20.04 LTS focal
Fixed 1.142.3
18.04 LTS bionic
Fixed 1.93.18
16.04 LTS xenial
Fixed 1.66.26
14.04 LTS trusty
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
20.04 LTS focal
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Vulnerable
14.04 LTS trusty Not in release

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Notes

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

sbeattie

809f3a268 script: Avoid a use-after-free when redefining a function during execution

Severity score breakdown

Parameter Value
Base score 6.4 · Medium
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