CVE-2023-4535VulnerabilityPublished 6 Nov 2023Updated 21 Nov 2025

CVE-2023-4535: Red Hat Enterprise Linux 9 · Out-of-bounds Read

Affects Red Hat Enterprise Linux 9Source CVE Database V5

Not known to be exploited · CVSS 4.5 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

4.5Medium

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: 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: 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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Nov 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 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

AI-suggested

1. Monitor for and restrict physical access to critical systems, especially those using smart cards or USB tokens for authentication. 2. Implement strict device control policies to prevent unauthorized USB devices from connecting to sensitive systems. 3. Apply vendor patches and updates promptly once available from Red Hat or OpenSC maintainers. 4. Employ endpoint security solutions capable of detecting anomalous device interactions or malformed APDU communications. 5. Conduct regular audits of hardware token usage and access logs to identify suspicious activity. 6. Consider additional layers of authentication or encryption that do not solely rely on vulnerable hardware drivers. 7. Educate staff on the risks of physical device insertion and enforce policies against connecting untrusted devices. 8. Use hardware security modules (HSMs) or alternative cryptographic solutions where feasible to reduce reliance on vulnerable drivers.

Description

An out-of-bounds read vulnerability was found in OpenSC packages within the MyEID driver when handling symmetric key encryption. Exploiting this flaw requires an attacker to have physical access to the computer and a specially crafted USB device or smart card. This flaw allows the attacker to manipulate APDU responses and potentially gain unauthorized access to sensitive data, compromising the system's security.

Impact

For European organizations, the impact of CVE-2023-4535 can be significant in environments where smart cards or USB security tokens are used for authentication or cryptographic operations on Red Hat Enterprise Linux 9 systems. Successful exploitation could lead to unauthorized access to sensitive credentials or cryptographic keys, undermining the confidentiality and integrity of protected data. This could facilitate further attacks such as privilege escalation or lateral movement within networks. Availability impact is also possible if the system becomes unstable due to malformed device interactions. Sectors like finance, government, healthcare, and critical infrastructure that rely on hardware tokens for strong authentication are particularly at risk. The requirement for physical access limits remote exploitation but raises concerns about insider threats or physical security breaches. The medium severity rating reflects the balance between the potential impact and the exploitation complexity.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 21 Nov 2025, 06:58 UTC

Technical details

References

Community reviews

Related threats