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CVE-2021-3418

Published: 2 March 2021

If certificates that signed grub are installed into db, grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown, yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism.

Notes

AuthorNote
sbeattie
does not affect grub2 as packaged in Ubuntu, we already had
to address CVE-2020-15705.
sbeattie
grub2-unsigned will contain fixes and supersede grub2, which will contain only BIOS grub bits.

Priority

Medium

Cvss 3 Severity Score

6.4

Score breakdown

Status

Package Release Status
grub2
Launchpad, Ubuntu, Debian
bionic Not vulnerable

focal Not vulnerable

groovy Not vulnerable

hirsute Not vulnerable

impish Not vulnerable

jammy Not vulnerable

trusty Not vulnerable

upstream Not vulnerable

xenial Not vulnerable

grub2-signed
Launchpad, Ubuntu, Debian
bionic Not vulnerable

focal Not vulnerable

groovy Not vulnerable

hirsute Not vulnerable

impish Not vulnerable

jammy Not vulnerable

trusty Not vulnerable

upstream Needs triage

xenial Not vulnerable

grub2-unsigned
Launchpad, Ubuntu, Debian
bionic Not vulnerable

focal Not vulnerable

groovy Not vulnerable

hirsute Not vulnerable

impish Not vulnerable

jammy Not vulnerable

trusty Not vulnerable

upstream Needs triage

xenial Not vulnerable

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