VulnerabilityPublished 9 Oct 2023Updated 6 Nov 2025

CVE-2023-39189: Red Hat Enterprise Linux 8 · Out-of-bounds Read

Affects Red Hat Enterprise Linux 8Source CVE Database V5

Not known to be exploited · CVSS 5.1 Medium.

Data as of 26 Oct 2026, 12:29 UTC

CVSS 3.1 base score

5.1Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: 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: None: There is no loss of integrity within 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 9 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

AI-suggested

European organizations should prioritize applying official patches from Red Hat as soon as they become available to address this vulnerability. Until patches are deployed, it is critical to restrict CAP_NET_ADMIN capabilities to only trusted and necessary users or processes, minimizing the number of accounts that can exploit this flaw. Implement strict access controls and monitoring on systems running RHEL 8 to detect any unauthorized privilege escalations or suspicious local activity. Employ kernel hardening techniques such as SELinux policies to limit the impact of potential exploits. Regularly audit user privileges and remove unnecessary CAP_NET_ADMIN capabilities. Consider deploying intrusion detection systems that monitor kernel-level anomalies or crashes. For environments with high security requirements, isolate critical systems and limit local access to reduce exposure. Maintain up-to-date backups and incident response plans to quickly recover from potential crashes or data leaks.

Description

A flaw was found in the Netfilter subsystem in the Linux kernel. The nfnl_osf_add_callback function did not validate the user mode controlled opt_num field. This flaw allows a local privileged (CAP_NET_ADMIN) attacker to trigger an out-of-bounds read, leading to a crash or information disclosure.

Impact

For European organizations, this vulnerability poses a risk primarily to confidentiality and system stability. Organizations using Red Hat Enterprise Linux 8 in multi-user environments or with delegated administrative privileges could face information disclosure if an attacker gains CAP_NET_ADMIN rights. This could lead to leakage of sensitive kernel memory contents, potentially exposing cryptographic keys, passwords, or other confidential data. Additionally, exploitation could cause kernel crashes, resulting in denial of service and operational disruptions. Critical sectors such as finance, government, telecommunications, and cloud service providers in Europe that rely heavily on RHEL 8 servers are particularly vulnerable. The requirement for local privileged access limits remote exploitation but insider threats or compromised accounts could leverage this flaw. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits post-disclosure. The impact on availability is limited but could affect high-availability services if crashes occur.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 6 Nov 2025, 20:57 UTC

Technical details

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