VulnerabilityPublished 3 Aug 2023Updated 6 Nov 2025

CVE-2023-4133: Red Hat Enterprise Linux 8 · Use After Free

Affects Red Hat Enterprise Linux 8Source CVE Database V5

Not known to be exploited · CVSS 5.5 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

5.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
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: 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: 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 3 Aug 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

Apply official patches from Red Hat as soon as they become available to address the use-after-free condition in the cxgb4 driver.
Restrict local access to systems running Red Hat Enterprise Linux 8, especially limiting untrusted or low-privileged user accounts that could attempt to exploit this vulnerability.
Monitor system logs and kernel messages for crashes or anomalies related to the cxgb4 driver or flower_stats_timer activity.
If patching is delayed, consider disabling or unloading the cxgb4 driver where feasible, particularly on systems not requiring Chelsio network adapters, to eliminate the attack surface.
Implement strict access controls and endpoint security measures to prevent unauthorized local access.
Conduct regular security audits and vulnerability scans to detect unpatched systems.
Educate system administrators about the vulnerability and the importance of timely patch management.
For critical infrastructure, consider deploying redundant systems or failover mechanisms to mitigate potential downtime from exploitation.

Description

A use-after-free vulnerability was found in the cxgb4 driver in the Linux kernel. The bug occurs when the cxgb4 device is detaching due to a possible rearming of the flower_stats_timer from the work queue. This flaw allows a local user to crash the system, causing a denial of service condition.

Impact

For European organizations, the primary impact of CVE-2023-4133 is the potential for local denial of service, which can disrupt business-critical applications and services running on Red Hat Enterprise Linux 8 systems using the cxgb4 driver. This could affect data centers, cloud providers, and enterprises relying on Chelsio network adapters for high-speed networking. Although the vulnerability does not expose sensitive data or allow privilege escalation, the ability of a low-privileged local user to crash the system can lead to operational downtime, loss of availability, and potential cascading effects on dependent services. Organizations in sectors such as finance, telecommunications, healthcare, and government, where uptime and service continuity are paramount, may experience significant operational risks. Additionally, the need for local access to exploit the vulnerability means that insider threats or compromised user accounts pose the greatest risk. The absence of known exploits reduces immediate threat levels but does not eliminate the risk of future exploitation. Therefore, European organizations must proactively address this vulnerability to maintain system stability and service availability.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 6 Nov 2025, 21:01 UTC

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