CVE-2023-6478 is a vulnerability identified in the xorg-server component of Red Hat Enterprise Linux 6 Extended Lifecycle Support (ELS). The flaw arises from an integer overflow or wraparound condition triggered by specially crafted requests to the RRChangeProviderProperty or RRChangeOutputProperty functions, which are part of the X Resize, Rotate and Reflect Extension (RandR) used for dynamic screen configuration. When these functions process input values without proper bounds checking, the integer overflow can occur, potentially causing memory corruption or unexpected behavior. This flaw can be exploited remotely over the network (AV:N) with low attack complexity (AC:L), requiring privileges (PR:L) but no user interaction (UI:N). The impact primarily affects confidentiality (C:H), with limited integrity (I:L) and availability (A:L) consequences. An attacker with limited privileges could leverage this vulnerability to disclose sensitive information from the affected system, possibly gaining insights into memory contents or other protected data. Although no known exploits are currently reported in the wild, the high CVSS score of 7.6 indicates a significant risk, especially in environments where RHEL 6 ELS is still in use. The vulnerability is particularly relevant for legacy systems that continue to rely on xorg-server for graphical interface management. Given that RHEL 6 is an older platform under Extended Lifecycle Support, organizations may face challenges in patching promptly, increasing exposure risk. The vulnerability was published on December 13, 2023, and assigned by Red Hat, highlighting the need for immediate attention from system administrators managing affected systems.

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.

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.