CVE-2023-6121VulnerabilityPublished 16 Nov 2023Updated 6 Nov 2025

CVE-2023-6121: Red Hat Enterprise Linux 8 · Out-of-bounds Read

Affects Red Hat Enterprise Linux 8Source CVE Database V5

Not known to be exploited · CVSS 4.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

4.3Medium

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

EPSS: 1.6% chance of exploitation in 30 days – higher than 76% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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: 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: 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 16 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

European organizations should implement the following specific mitigations: 1) Immediately monitor Red Hat security advisories and apply kernel updates or patches addressing CVE-2023-6121 once available. 2) If NVMe-oF/TCP is not required, disable the subsystem to eliminate the attack surface. 3) Restrict network access to NVMe-oF/TCP services using firewall rules and network segmentation to limit exposure to untrusted networks. 4) Regularly audit kernel ring buffer logs (dmesg) for unusual or unexpected memory leak messages that could indicate exploitation attempts. 5) Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and strict access controls to reduce the impact of information disclosure. 6) In virtualized or containerized environments, ensure isolation boundaries are enforced to prevent cross-tenant data leakage. 7) Conduct vulnerability scanning and penetration testing focused on NVMe-oF/TCP implementations to identify potential exploitation paths. 8) Educate system administrators about this vulnerability and the importance of timely patching and monitoring.

Description

An out-of-bounds read vulnerability was found in the NVMe-oF/TCP subsystem in the Linux kernel. This issue may allow a remote attacker to send a crafted TCP packet, triggering a heap-based buffer overflow that results in kmalloc data being printed and potentially leaked to the kernel ring buffer (dmesg).

Impact

For European organizations, the primary impact of CVE-2023-6121 is the potential leakage of sensitive kernel memory information, which could be leveraged by attackers to facilitate further attacks such as privilege escalation or kernel-level exploits. Although the vulnerability does not directly cause denial of service or code execution, the information disclosure risk can compromise system confidentiality and security posture. Organizations relying on Red Hat Enterprise Linux 8 in critical infrastructure, financial services, telecommunications, and government sectors may face increased risk if NVMe-oF/TCP is enabled and exposed to untrusted networks. The medium severity rating reflects the limited scope and complexity but does not diminish the importance of timely remediation, especially in environments with stringent data protection requirements under GDPR. Additionally, the vulnerability could be exploited in multi-tenant cloud environments where kernel memory leaks might expose data across tenants. The lack of known exploits reduces immediate risk but does not preclude future exploitation attempts.

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What to do

Description

AI analysisMachine-generated, updated 6 Nov 2025, 21:00 UTC

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