CVE-2026-97876Public exploit

Unsigned module execution via serial MMIO overwrite

Published Oct 2, 2026 · Updated Oct 2, 2026

Lockdown bypass in GNU GRUB 2.14 allows attackers controlling boot configuration to load unsigned modules during Secure Boot. The serial command accepts an unchecked MMIO base, so UART initialization writes to the chosen address can clear the grub_file_verifiers list and disable module verification. The demonstrated path requires an accepted boot configuration, an admitted signed image, knowledge of its loaded address, and a serial input poll; execution was shown only in GRUB's pre-OS environment.

CVSS severity6.4
Medium
EPSS probability0.11%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Lockdown bypass in GNU GRUB 2.14 allows attackers controlling boot configuration to load unsigned modules during Secure Boot. The serial command accepts an unchecked MMIO base, so UART initialization writes to the chosen address can clear the grub_file_verifiers list and disable module verification. The demonstrated path requires an accepted boot configuration, an admitted signed image, knowledge of its loaded address, and a serial input poll; execution was shown only in GRUB's pre-OS environment.

The record

CVE
CVE-2026-97876
Published
Oct 2, 2026
Updated
Oct 2, 2026
Vendor
CVS Home
Product
GNU GRUB
Classifications
CWE-822, T1553
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Oct 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.12 <2.16

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

CVS Home · GNU GRUBversion=2.12 <2.16

Published CVSS scores

6.4Public disclosure authorCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-822Untrusted Pointer Dereference
T1553Subvert Trust Controls

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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