CVE-2026-97876
Bypass of GRUB lockdown restriction in Secure Boot mode via serial command MMIO base address
- State
- Published
- Severity
- 6.4 Medium
- Published
- Oct 2, 2026
- Updated
- Oct 2, 2026
- Reserved
- Sep 25, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.4 Medium | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H | canonical |
Weaknesses
- CWE-822 Untrusted pointer dereference
Affected Products
| Product | Versions |
|---|---|
grub2GNU |
|
References
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.