CVE-2021-3418
If certificates that signed grub are installed into db, grub can be booted directly. It will then...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2021-3418- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 4.4 Medium
AV:L/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-281
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2021-3418- Weakness
- CWE-281
- Updated
- 2026-11-02
EUVDEUVD-2021-26746 No score
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.
- Record
EUVD-2021-26746- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-j6wm-c7q8-jcx7 No score
If certificates that signed grub are installed into db, grub can be booted directly. It will then...
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 grbu2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism.
- Record
GHSA-j6wm-c7q8-jcx7- Weakness
- CWE-281
- Updated
- 2026-11-02
OSVALPINE-CVE-2021-3418
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.
- Record
ALPINE-CVE-2021-3418- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVAZL-6467
CVE-2021-3418 affecting package grub2 for versions less than 2.06~rc1-7
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.
- Record
AZL-6467- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVBELL-CVE-2021-3418
CVE-2021-3418 does not affect BellSoft software
- Record
BELL-CVE-2021-3418- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-3418- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
grubAlpine:v3.17 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.18 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.19 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.20 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.21 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.22 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.23 |
before 2.06-r0 | 2.06-r0 |
grubAlpine:v3.24 |
before 2.06-r0 | 2.06-r0 |
grub2Azure Linux:2 |
before 2.06~rc1-7 | 2.06~rc1-7 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-3418 is a medium vulnerability (CVSS 6.4) in Gnu Grub2, published March 15, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 40th percentile. Fixed in grub 2.06-r0.