CVE-2023-6478VulnerabilityPublished 13 Dec 2023Updated 20 Nov 2025

CVE-2023-6478: Red Hat Enterprise Linux 6 Extended Lifecycle Support – EXTENSION · Integer Overflow or Wraparound

Affects Red Hat Enterprise Linux 6 Extended Lifecycle Support – EXTENSIONSource CVE Database V5

Not known to be exploited · CVSS 7.6 High.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.6High

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:L/UI:N/S:U/C:H/I:L/A:L

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

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: 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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 13 Dec 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 2026-10-26.

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 for RHEL 6 ELS systems to address the integer overflow in xorg-server. 2. If patches are delayed or unavailable, consider disabling or restricting access to the X server and RandR extension interfaces, especially RRChangeProviderProperty and RRChangeOutputProperty, to limit exposure. 3. Implement strict network segmentation and firewall rules to restrict access to graphical server ports only to trusted and necessary users or systems. 4. Enforce the principle of least privilege by limiting user and process permissions that can interact with the X server, reducing the risk of exploitation by low-privileged attackers. 5. Monitor system logs and network traffic for unusual or malformed requests targeting RandR functions or the X server, enabling early detection of exploitation attempts. 6. Where feasible, plan and accelerate migration away from legacy RHEL 6 ELS systems to supported versions with active security maintenance. 7. Conduct regular security audits and vulnerability assessments focusing on legacy infrastructure components to identify and remediate similar risks proactively.

Description

A flaw was found in xorg-server. A specially crafted request to RRChangeProviderProperty or RRChangeOutputProperty can trigger an integer overflow which may lead to a disclosure of sensitive information.

Impact

For European organizations, the primary impact of CVE-2023-6478 is the potential unauthorized disclosure of sensitive information from systems running Red Hat Enterprise Linux 6 ELS with xorg-server. This can compromise confidentiality of critical data, including credentials, configuration details, or other sensitive memory contents. Although the vulnerability does not directly allow code execution or system takeover, information leaks can facilitate further attacks or lateral movement within networks. Organizations in sectors such as government, finance, healthcare, and critical infrastructure that still operate legacy RHEL 6 systems with graphical interfaces are particularly vulnerable. The risk is exacerbated in environments where privileged users have network access to the X server, as the exploit requires some privilege level but no user interaction. The limited availability and integrity impact reduce the likelihood of service disruption or data tampering but do not eliminate the threat of espionage or data leakage. The absence of known exploits in the wild provides a window for proactive mitigation, but the high severity score demands urgent remediation to prevent future exploitation. Legacy systems in European organizations often persist due to operational constraints, making this vulnerability a significant concern for maintaining compliance with data protection regulations such as GDPR.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 20 Nov 2025, 07:30 UTC

Technical details

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