Medium severity · published Mar 15, 2021
CVE-2021-3418
If certificates that signed grub are installed into db, grub can be booted directly
6.4
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
High
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GR
Grub2 · Gnu
before 2.06 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3418
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-3418
Issue Tracking
https://bugzilla.redhat.com/show_bug.cgi?id=1933757
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