CVE-2026-97876
Bypass of GRUB lockdown restriction in Secure Boot mode via serial command MMIO base address
At a glance
- Source
- NVD
- EPSS
- EPSS 0.11 % · percentile 2 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- canonical
- NVD status
- Awaiting Analysis
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.
Weaknesses (CWE)
- CWE-822 — Untrusted Pointer Dereference
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 6.4 | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H | canonical |
| CVSS 3.1 | MEDIUM 6.4 | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H | NVD · security@ubuntu.com (Secondary) |
European references
- ENISA EUVD · EUVD-2026-91376
- GCVE · GCVE-0-2026-97876
Affected products
| Product | Versions |
|---|---|
| GNU · grub2 | affected 2.12 < 2.16 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |