CVE-2023-42756VulnerabilityPublished 28 Sep 2023Updated 6 Nov 2025

CVE-2023-42756: Red Hat Enterprise Linux 9 · Race Condition

Affects Red Hat Enterprise Linux 9Source CVE Database V5

Not known to be exploited · CVSS 4.4 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

4.4Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 19% 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:N/I:N/A:H

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within 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 28 Sep 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. Apply official patches from Red Hat as soon as they become available to address the race condition in the Netfilter subsystem. 2. Restrict local administrative access strictly to trusted personnel and use multi-factor authentication to reduce the risk of privilege escalation. 3. Implement robust monitoring of kernel logs and system stability metrics to detect early signs of kernel panics or abnormal behavior related to IP sets. 4. Employ security best practices such as SELinux enforcing mode and system integrity verification to limit the impact of potential exploitation. 5. Use configuration management tools to ensure consistent and rapid deployment of patches across all affected systems. 6. Conduct regular audits of user privileges and remove unnecessary elevated rights to minimize the attack surface. 7. Consider network segmentation to isolate critical systems and limit the potential spread of denial-of-service impacts. 8. Educate system administrators about this vulnerability and the importance of timely patching and monitoring.

Description

A flaw was found in the Netfilter subsystem of the Linux kernel. A race condition between IPSET_CMD_ADD and IPSET_CMD_SWAP can lead to a kernel panic due to the invocation of `__ip_set_put` on a wrong `set`. This issue may allow a local user to crash the system.

Impact

For European organizations, this vulnerability primarily threatens system availability by enabling local privileged users to crash affected systems running Red Hat Enterprise Linux 9. This can disrupt critical services, especially in environments relying on stable firewall and network filtering capabilities. Organizations operating data centers, cloud infrastructure, or critical industrial control systems with Red Hat Enterprise Linux 9 are at risk of denial-of-service incidents if attackers gain local privileged access. Although the vulnerability does not expose data confidentiality or integrity, the resulting downtime could impact business operations, regulatory compliance, and service level agreements. The requirement for local high privileges limits the risk from remote attackers but elevates the threat from insider threats or attackers who have already compromised user accounts with elevated rights. European sectors such as finance, healthcare, telecommunications, and government, which often deploy Red Hat Enterprise Linux in their infrastructure, could face operational disruptions if this vulnerability is exploited.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 6 Nov 2025, 20:59 UTC

Technical details

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