Ubuntu.comUB:CVE-2021-3418CVE-2021-3418
CVSS2
Attack Vector
LOCAL
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:M/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
33.3%
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
| Author | Note |
|---|---|
| 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. |
Related
CVSS2
Attack Vector
LOCAL
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:M/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
33.3%