4.6 Medium
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
8.2 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
8.6 High
AI Score
Confidence
High
0.002 Low
EPSS
Percentile
61.9%
USN-4432-1 fixed vulnerabilities in GRUB2 affecting Secure Boot
environments. Unfortunately, the update introduced regressions for
some BIOS systems (either pre-UEFI or UEFI configured in Legacy mode),
preventing them from successfully booting. This update addresses
the issue.
Users with BIOS systems that installed GRUB2 versions from USN-4432-1
should verify that their GRUB2 installation has a correct understanding
of their boot device location and installed the boot loader correctly.
We apologize for the inconvenience.
Original advisory details:
Jesse Michael and Mickey Shkatov discovered that the configuration parser
in GRUB2 did not properly exit when errors were discovered, resulting in
heap-based buffer overflows. A local attacker could use this to execute
arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-10713)
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. (CVE-2020-15706)
Chris Coulson discovered that multiple integer overflows existed in GRUB2
when handling certain filesystems or font files, leading to heap-based
buffer overflows. A local attacker could use these to execute arbitrary
code and bypass UEFI Secure Boot restrictions. (CVE-2020-14309,
CVE-2020-14310, CVE-2020-14311)
It was discovered that the memory allocator for GRUB2 did not validate
allocation size, resulting in multiple integer overflows and heap-based
buffer overflows when handling certain filesystems, PNG images or disk
metadata. A local attacker could use this to execute arbitrary code and
bypass UEFI Secure Boot restrictions. (CVE-2020-14308)
Mathieu Trudel-Lapierre discovered that in certain situations, GRUB2
failed to validate kernel signatures. A local attacker could use this
to bypass Secure Boot restrictions. (CVE-2020-15705)
Colin Watson and Chris Coulson discovered that an integer overflow
existed in GRUB2 when handling the initrd command, leading to a heap-based
buffer overflow. A local attacker could use this to execute arbitrary code
and bypass UEFI Secure Boot restrictions. (CVE-2020-15707)
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
Ubuntu | 20.04 | noarch | grub-efi-amd64-bin | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-common | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-common-dbgsym | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-coreboot | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-coreboot-bin | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-coreboot-dbg | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-efi | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-efi-amd64 | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-efi-amd64-dbg | < 2.04-1ubuntu26.2 | UNKNOWN |
Ubuntu | 20.04 | noarch | grub-efi-amd64-signed-template | < 2.04-1ubuntu26.2 | UNKNOWN |
4.6 Medium
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
8.2 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
8.6 High
AI Score
Confidence
High
0.002 Low
EPSS
Percentile
61.9%