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TI-2021-02383 Aliases CVE-2021-3418GHSA-j6wm-c7q8-jcx7

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

Priority LOW 29CWE-281Published · Updated

Key facts

Attack vector
Local
Privileges required
High
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Microsoft.

Summary

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.

Why it matters now

EPSS 0.00466 40th percentileScored 2026-11-07
Fix Fixed Microsoft: 1 update

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
—grub2Fixed in 2.06—No fix listedCNA
  • grub2 Vendor— Affected Fixed in 2.06 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:gnu:grub2:*:*:*:*:*:*:*:*before 2.06VulnerableGNU
  • cpe:2.3:a:gnu:grub2:*:*:*:*:*:*:*:* Versions before 2.06 Vulnerable ·GNU

Remediation

Microsoft 1 update

  • ADV200011 Released 2020-07-29
    Microsoft Guidance for Addressing Security Feature Bypass in GRUB

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 2 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-3418
  2. 2026-10-03 Alias added: GHSA-j6wm-c7q8-jcx7

References

Advisory 1

  • TI-2023-04324 Grub2: out-of-bounds write at fs/ntfs.c may lead to unsigned code execution CVSS 3.1HIGH 7.8
  • TI-2015-06891 Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate… CVSS 3.1HIGH 7.4
  • TI-2024-37620 Heap-based buffer overflow in GNU GRUB2 CVSS 3.1HIGH 8.8
  • TI-2022-11367 Integer underflow in GNU GRUB CVSS 3.1HIGH 8.1
  • TI-2022-02403 Heap-based buffer overflow in grub2 CVSS 3.1HIGH 8.6
  • TI-2020-08612 Buffer overflow in Grub CVSS 3.1HIGH 8.2
See all 47 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences