CVE-2023-4813 is a use-after-free vulnerability identified in the GNU C Library (glibc), specifically within the gaih_inet function used by the getaddrinfo API call. This flaw manifests under a rare condition where the hosts database configuration in /etc/nsswitch.conf includes the SUCCESS=continue or SUCCESS=merge options. When these options are set, the gaih_inet function may attempt to access memory that has already been freed, causing an application crash. This vulnerability affects Red Hat Enterprise Linux 8 systems that use glibc and have the specified nsswitch.conf configuration. The vulnerability does not impact confidentiality or integrity but can cause denial-of-service by crashing applications relying on getaddrinfo, which is commonly used for hostname resolution. The CVSS v3.1 score is 5.9 (medium), reflecting network attack vector, high attack complexity, no privileges required, no user interaction, and impact limited to availability. No public exploits or active exploitation have been reported to date. The issue is mitigated by applying patches to glibc and adjusting the nsswitch.conf file to avoid the problematic SUCCESS=continue or SUCCESS=merge options for the hosts database. This vulnerability highlights the importance of careful configuration of name resolution services and timely patching of core system libraries.

For European organizations, the primary impact of CVE-2023-4813 is the potential for denial-of-service conditions on critical Linux-based systems running Red Hat Enterprise Linux 8. Applications that rely on getaddrinfo for hostname resolution may crash unexpectedly, disrupting services such as web servers, mail servers, and other networked applications. This can affect availability of IT services, potentially leading to operational downtime and loss of productivity. Since the vulnerability does not compromise confidentiality or integrity, data breaches are unlikely. However, availability disruptions in sectors like finance, healthcare, telecommunications, and government could have significant operational and reputational consequences. Organizations with customized or non-default nsswitch.conf configurations are at higher risk. The absence of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to prevent future exploitation or accidental service outages.

1. Apply official Red Hat patches or updates to glibc as soon as they become available to eliminate the use-after-free condition. 2. Review and modify the /etc/nsswitch.conf file to avoid using SUCCESS=continue or SUCCESS=merge options for the hosts database, reverting to default or safer configurations. 3. Conduct thorough testing of applications that rely on getaddrinfo to ensure stability after configuration changes or patching. 4. Implement monitoring and alerting for application crashes related to name resolution failures to detect potential exploitation or misconfigurations early. 5. Maintain an inventory of systems running Red Hat Enterprise Linux 8 and prioritize patching on critical infrastructure and internet-facing servers. 6. Educate system administrators about the risks of non-standard nsswitch.conf configurations and encourage adherence to best practices. 7. Consider network segmentation and limiting exposure of vulnerable services to reduce attack surface. 8. Regularly audit system logs for anomalies related to DNS resolution and application crashes.