VulnerabilityPublished 25 Sep 2023Updated 18 Dec 2025

CVE-2023-5156: Red Hat Enterprise Linux 6 · Memory Leak

Affects Red Hat Enterprise Linux 6Source CVE Database V5

Mentioned vulnerabilities

CVE-2023-4806

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 1.6% chance of exploitation in 30 days – higher than 75% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
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: 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: 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: 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 25 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 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 memory leak directly.
Until patches are released, implement monitoring of memory usage for critical applications and services running on RHEL 6 to detect abnormal consumption patterns early.
Limit network exposure of vulnerable services by using firewalls and network segmentation to reduce the attack surface.
Consider upgrading from RHEL 6 to a more recent, supported version of Red Hat Enterprise Linux to benefit from improved security and memory management.
Employ application-level watchdogs or automated restart mechanisms to recover services that crash due to memory exhaustion.
Conduct thorough testing of applications after patch deployment to ensure stability and performance.
Maintain an incident response plan that includes procedures for handling denial of service incidents related to memory leaks.

Description

A flaw was found in the GNU C Library. A recent fix for CVE-2023-4806 introduced the potential for a memory leak, which may result in an application crash.

Impact

For European organizations, the primary impact of CVE-2023-5156 is on system availability. Applications running on RHEL 6 that depend on the GNU C Library may experience memory exhaustion leading to crashes or denial of service, potentially disrupting critical business operations and services. This can affect enterprise environments, government agencies, and infrastructure providers still operating legacy RHEL 6 systems. Although confidentiality and integrity are not directly compromised, the operational disruption can have cascading effects, including loss of productivity, service outages, and increased operational costs. The vulnerability's remote exploitability without authentication means attackers can potentially trigger crashes from outside the network, increasing the risk of widespread denial of service attacks. Organizations with legacy systems or those that have delayed upgrades are at heightened risk. The absence of known exploits provides a window for proactive mitigation but also underscores the need for vigilance.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 19 Dec 2025, 04:26 UTC

Technical details

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