CVE-2023-4001Public exploit

Physical authentication bypass via duplicate filesystem UUID

Published Jan 15, 2024 · Updated Nov 20, 2025

Authentication bypass in Red Hat Enterprise Linux 9 GRUB allows physically proximate attackers to access the GRUB shell via a USB drive. The UEFI stub grub.cfg searches every enumerated block device for the /boot filesystem UUID and accepts an attacker-controlled duplicate before the internal disk, so the password-bearing main configuration never runs. The target must use the affected downstream grub2 patch, configured GRUB password protection, and UEFI firmware that enumerates removable media first; exploitation exposes an unauthenticated bootloader shell.

CVSS severity6.8
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Red Hat Enterprise Linux 9 GRUB allows physically proximate attackers to access the GRUB shell via a USB drive. The UEFI stub grub.cfg searches every enumerated block device for the /boot filesystem UUID and accepts an attacker-controlled duplicate before the internal disk, so the password-bearing main configuration never runs. The target must use the affected downstream grub2 patch, configured GRUB password protection, and UEFI firmware that enumerates removable media first; exploitation exposes an unauthenticated bootloader shell.

The record

CVE
CVE-2023-4001
Published
Jan 15, 2024
Updated
Nov 20, 2025
Vendor
Red Hat
Product
Red Hat Enterprise Linux 9.0 Extended Update Support
Classifications
CWE-290, T1068
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 20, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 9.0 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.2 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

6.8Red HatCVSS:3.1/AV:P/AC:L/PR:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1068Exploitation for Privilege Escalation

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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Your stack

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