CVE-2021-3418

Name: CVE-2021-3418
Creator: NVD / NIST
Published: 2021-03-15T22:15:13.907+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.4/10EPSS 0.48%

Last modified Jun 17, 2026

CVE-2021-3418 is a medium-severity vulnerability rated 6.4/10 on the CVSS scale. If certificates that signed grub are installed into db, grub can be booted directly. It will then boot any kernel without signature validation. EPSS estimates a 0.48% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

6.4/10

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.48%

37.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-281

Affected Software

Vendor	Product	Versions
Gnu	Grub2	< 2.06

References

https://bugzilla.redhat.com/show_bug.cgi?id=1933757Issue Tracking, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1933757Issue Tracking, Third Party Advisory

Timeline

Published: Mar 15, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3418?

How severe is CVE-2021-3418?

CVE-2021-3418 has a CVSS score of 6.4/10 (MEDIUM severity). The EPSS model estimates a 0.48% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3418?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3418?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST