VulnerabilityPublished 25 Oct 2023Updated 7 Nov 2025

CVE-2023-4693: Red Hat Enterprise Linux 8 grub2 · Out-of-bounds Read

Affects Red Hat Enterprise Linux 8 grub2Source CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 12:54 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: High
Privileges Required: High
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: None
Availability: None

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

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
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: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Oct 2023
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 26 Oct 2026.

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 or the CVSS exploit maturity 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 Hatredhat/grub2`pkg:rpm/redhat/grub2`Other threats	Affected =2.06-93.el8_9.1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Apply official patches from Red Hat as soon as they become available to address the grub2 NTFS driver vulnerability.
Restrict physical access to systems running Red Hat Enterprise Linux 8, especially those with grub2 NTFS support enabled, through enhanced physical security controls such as locked server rooms and surveillance.
Disable or remove NTFS filesystem support in grub2 if it is not required for operational purposes to reduce the attack surface.
Implement secure boot and EFI variable protection mechanisms to limit unauthorized reading or modification of EFI variables.
Regularly audit and monitor physical access logs and system boot configurations for anomalies.
Use full disk encryption to protect data at rest, which may mitigate some risks of memory disclosure during boot.
Educate system administrators about the risks of physical access attacks and ensure strict privilege management to prevent unauthorized local access.
Maintain up-to-date backups and recovery procedures to mitigate potential indirect consequences of confidentiality breaches.

Description

An out-of-bounds read flaw was found on grub2's NTFS filesystem driver. This issue may allow a physically present attacker to present a specially crafted NTFS file system image to read arbitrary memory locations. A successful attack allows sensitive data cached in memory or EFI variable values to be leaked, presenting a high Confidentiality risk.

Impact

For European organizations, the primary impact of CVE-2023-4693 is the potential leakage of sensitive information from memory and EFI variables on affected RHEL 8 systems. This can compromise confidentiality of critical boot parameters and cached data, which may include cryptographic keys or system configuration details. Organizations with physical access controls that are weak or environments where attackers can gain local access (e.g., data centers, branch offices, or shared facilities) are at higher risk. The vulnerability does not allow remote exploitation, limiting its impact to scenarios involving insider threats or physical breaches. Confidentiality breaches could facilitate further attacks or unauthorized system modifications if attackers gain knowledge of EFI variables. The lack of integrity or availability impact reduces the risk of system disruption but does not diminish the importance of protecting sensitive data. European sectors such as finance, government, and critical infrastructure that rely on RHEL 8 for secure boot and system integrity should consider this vulnerability significant. The absence of known exploits in the wild reduces immediate risk but does not eliminate the need for mitigation.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2025, 19:57 UTC

Technical details

References

Community reviews

Related threats