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CVE-2021-3418

6.4 · MEDIUM

If certificates that signed grub are installed into db, grub can be booted directly.

Published Mar 15, 2021CWE-281EPSS 0.47%

Overview

CVE-2021-3418 is a medium-severity vulnerability. It was published on March 15, 2021 and has a CVSS 3.1 base score of 6.4 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.4, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refbugzilla.redhat.com/show_bug.cgi?id=1933757Refbugzilla.redhat.com/show_bug.cgi?id=1933757

How CyberStrike helps

Frequently asked questions

What is CVE-2021-3418?

CVE-2021-3418 is a medium-severity vulnerability. It was published on March 15, 2021 and has a CVSS 3.1 base score of 6.4 (MEDIUM).

How severe is CVE-2021-3418?

This vulnerability has a CVSS 3.1 base score of 6.4, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-3418?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-3418?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-3418 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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