CVE-2020-27779
Published: 2 March 2021
A flaw was found in grub2 in versions prior to 2.06. The cutmem command does not honor secure boot locking allowing an privileged attacker to remove address ranges from memory creating an opportunity to circumvent SecureBoot protections after proper triage about grub's memory layout. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
From the Ubuntu Security Team
It was discovered that the cutmem command in GRUB 2 did not honor secure boot locking. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions.
Notes
| Author | Note |
|---|---|
| sbeattie | grub2-unsigned will contain fixes and supersede grub2, which will contain only BIOS grub bits. |
Priority
Status
| Package | Release | Status |
|---|---|---|
|
grub2-signed Launchpad, Ubuntu, Debian |
hirsute |
Released
(1.164)
|
| xenial |
Pending
(1.164)
|
|
| focal |
Released
(1.167.2)
|
|
| groovy |
Released
(1.167.2)
|
|
| impish |
Released
(1.169)
|
|
| upstream |
Needs triage
|
|
| trusty |
Needed
|
|
| bionic |
Released
(1.167~18.04.5)
|
|
| jammy |
Not vulnerable
(1.180)
|
|
| lunar |
Not vulnerable
(1.192)
|
|
| kinetic |
Not vulnerable
(1.185)
|
|
|
grub2-unsigned Launchpad, Ubuntu, Debian |
bionic |
Released
(2.04-1ubuntu44.1.2)
|
| focal |
Released
(2.04-1ubuntu44.2)
|
|
| hirsute |
Released
(2.04-1ubuntu42)
|
|
| xenial |
Pending
(2.04-1ubuntu42)
|
|
| groovy |
Released
(2.04-1ubuntu44.2)
|
|
| impish |
Released
(2.04-1ubuntu45)
|
|
| upstream |
Needs triage
|
|
| trusty |
Does not exist
|
|
| jammy |
Not vulnerable
(2.06-2ubuntu7)
|
|
| kinetic |
Not vulnerable
(2.06-2ubuntu12)
|
|
| lunar |
Not vulnerable
(2.06-2ubuntu16)
|
|
|
grub2 Launchpad, Ubuntu, Debian |
trusty |
Needed
|
| xenial |
Needed
|
|
| bionic |
Needed
|
|
| focal |
Needed
|
|
| jammy |
Not vulnerable
(2.06-2ubuntu7)
|
|
| kinetic |
Not vulnerable
(2.06-2ubuntu12)
|
|
| lunar |
Not vulnerable
(2.06-2ubuntu16)
|
|
| upstream |
Needs triage
|
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 |