What is CVE-2021-3418?

CVE-2021-3418 is a medium-severity vulnerability in Gnu Grub2, classified under Improper Preservation of Permissions. CVSS score: 6.4/10. Published 2021-03-15.

How severe is CVE-2021-3418?

Medium severity. CVSS v3 base score is 6.4 out of 10.

Is CVE-2021-3418 known to be exploited?

25 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Gnu Grub2

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.

EPSS: 0.005 (37.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H.

Affected products

Gnu Grub2
N/a Grub2 — versions Fixed in 2.06

Weakness classification (CWE)

CWE-281 — Improper Preservation of Permissions

Public proof-of-concept exploits

References

secalert@redhat.com (Third Party Advisory, x_refsource_MISC, Issue Tracking)

Frequently asked questions

What is CVE-2021-3418?: CVE-2021-3418 is a medium-severity vulnerability in Gnu Grub2, classified under Improper Preservation of Permissions. CVSS score: 6.4/10. Published 2021-03-15.
How severe is CVE-2021-3418?: Medium severity. CVSS v3 base score is 6.4 out of 10.
Is CVE-2021-3418 known to be exploited?: 25 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.