Description
A local attacker with control over GRUB's configuration can bypass lockdown restrictions when booting with Secure Boot and load an unsigned GRUB module, while GRUB continues to report lockdown is enabled.




The vulnerability is caused by insufficient validation of the MMIO base address passed to the GRUB serial command. GRUB does not validate that the base address corresponds to a UART device, rather than being an arbitrary memory address. This allows an attacker to trick GRUB into writing non-arbitrary data at an attacker-controlled address, including resetting the grub_file_verifiers list in a way that disables the subsequent verification of loaded modules.
Published: 2026-10-02
Score: 6.4 Medium
EPSS: < 1% Very Low
KEV: No
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Sat, 03 Oct 2026 06:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Sat, 03 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Fri, 02 Oct 2026 11:45:00 +0000

Type Values Removed Values Added
First Time appeared Gnu
Gnu grub2
Vendors & Products Gnu
Gnu grub2

Fri, 02 Oct 2026 10:45:00 +0000

Type Values Removed Values Added
Description A local attacker with control over GRUB's configuration can bypass lockdown restrictions when booting with Secure Boot and load an unsigned GRUB module, while GRUB continues to report lockdown is enabled. The vulnerability is caused by insufficient validation of the MMIO base address passed to the GRUB serial command. GRUB does not validate that the base address corresponds to a UART device, rather than being an arbitrary memory address. This allows an attacker to trick GRUB into writing non-arbitrary data at an attacker-controlled address, including resetting the grub_file_verifiers list in a way that disables the subsequent verification of loaded modules.
Title Bypass of GRUB lockdown restriction in Secure Boot mode via serial command MMIO base address
Weaknesses CWE-822
References
Metrics cvssV3_1

{'score': 6.4, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: canonical

Published:

Updated: 2026-10-02T17:45:06.705Z

Reserved: 2026-09-25T08:49:34.867Z

Link: CVE-2026-97876

cve-icon Vulnrichment

Updated: 2026-10-02T17:44:59.967Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-02T11:17:39.727

Modified: 2026-10-02T18:44:11.270

Link: CVE-2026-97876

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-02T10:34:23Z

Links: CVE-2026-97876 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-02T12:00:15Z

Weaknesses
  • CWE-822

    Untrusted Pointer Dereference