CVE-2023-4001VulnerabilityPublished 15 Jan 2024Updated 20 Nov 2025

CVE-2023-4001: Red Hat Enterprise Linux 9 · Authentication Bypass by Spoofing

Affects Red Hat Enterprise Linux 9Source CVE Database V5

Not known to be exploited · CVSS 6.8 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

6.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Physical
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Physical: The attack requires the attacker to physically touch or manipulate the vulnerable component. Physical interaction may be brief or persistent.
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Jan 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Red Hat Red Hat Enterprise Linux 9	Affected =9	Fixed in–

AI-suggested

1. Apply official Red Hat patches for grub2 as soon as they are released to address the downstream patch issue causing this vulnerability. 2. Enforce strict physical security policies to prevent unauthorized personnel from accessing servers or workstations, including locked server rooms and restricted USB port access. 3. Disable or restrict booting from removable media in UEFI firmware settings where possible, to prevent boot order manipulation. 4. Implement BIOS/UEFI passwords to prevent unauthorized changes to boot order or firmware settings. 5. Use hardware-based security features such as Trusted Platform Module (TPM) and Secure Boot to ensure boot integrity and prevent unauthorized bootloader modifications. 6. Monitor and audit physical access logs and removable media usage in sensitive environments. 7. Educate system administrators and security teams about this vulnerability and the importance of physical security in mitigating it. 8. Consider additional endpoint protection solutions that can detect unauthorized bootloader tampering or abnormal boot sequences.

Description

CVE-2023-4001 is an authentication bypass vulnerability in Red Hat Enterprise Linux 9's GRUB bootloader. The flaw arises from GRUB's reliance on device UUIDs to locate the configuration file containing the GRUB password hash. An attacker with physical access can attach a removable drive (e.g. , USB stick) with a duplicate UUID matching the system's /boot partition. On UEFI systems that enumerate removable drives before fixed drives, this allows bypassing GRUB password protection, potentially leading to full system compromise. This vulnerability was introduced by a downstream patch in Red Hat's grub2 and does not affect upstream grub2. The CVSS score is 6.8 (medium severity), reflecting high impact but requiring physical access and specific conditions. No known exploits are currently in the wild.

Impact

The primary impact of CVE-2023-4001 is the bypass of GRUB password protection, which can lead to unauthorized bootloader access. This can result in attackers gaining control over boot parameters, loading unauthorized or malicious kernels, and ultimately compromising the entire system's confidentiality, integrity, and availability. For European organizations, especially those in critical infrastructure, finance, government, and enterprises relying on Red Hat Enterprise Linux 9 with UEFI systems, this vulnerability poses a significant risk of local privilege escalation and persistent compromise. The requirement for physical access limits remote exploitation but increases the threat in environments with less stringent physical security, such as shared offices, data centers with lax controls, or remote branch offices. The vulnerability could facilitate attacks such as firmware-level malware installation, bypassing disk encryption, or disabling security controls at boot time. This could lead to data breaches, service disruptions, and loss of trust. Given the widespread use of RHEL in European enterprises and public sector organizations, the impact could be substantial if mitigations are not applied promptly.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Nov 2025, 20:27 UTC

Technical details

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