CVE-2023-5157 is a vulnerability identified in MariaDB running on Red Hat Enterprise Linux 8, where an unauthenticated remote attacker can cause uncontrolled resource consumption leading to a denial of service (DoS). The issue arises when an OpenVAS port scan targets MariaDB default ports 3306 and 4567, triggering excessive resource usage that exhausts system resources and disrupts service availability. This vulnerability does not compromise data confidentiality or integrity but severely impacts system availability. The attack vector is network-based, requiring no privileges or user interaction, making it accessible to any remote attacker scanning these ports. The vulnerability was published on September 26, 2023, with a CVSS v3.1 score of 7.5 (high severity), reflecting its ease of exploitation and significant impact on availability. No patches or known exploits in the wild have been reported yet, but the potential for denial of service attacks against critical database services is significant. The vulnerability highlights the risk of exposing database ports directly to untrusted networks without adequate filtering or intrusion prevention measures. Organizations relying on MariaDB on Red Hat Enterprise Linux 8 should assess their exposure and implement network controls to mitigate this risk.

For European organizations, this vulnerability poses a significant risk to the availability of database services running MariaDB on Red Hat Enterprise Linux 8. Denial of service attacks can disrupt business operations, especially for sectors relying heavily on database availability such as finance, healthcare, telecommunications, and public services. The ease of exploitation without authentication means attackers can launch attacks remotely with minimal effort, potentially causing widespread service outages. This can lead to operational downtime, loss of customer trust, and financial losses. Additionally, critical infrastructure providers using these systems may face increased risk of service disruption, which could have cascading effects on dependent services. The lack of confidentiality or integrity impact reduces the risk of data breaches but does not diminish the operational threat posed by service unavailability. Organizations with exposed MariaDB ports on the internet are particularly vulnerable, emphasizing the need for immediate mitigation.

1. Restrict network access to MariaDB ports (3306 and 4567) using firewalls or network access control lists (ACLs) to allow only trusted hosts or internal networks. 2. Implement intrusion detection/prevention systems (IDS/IPS) to detect and block suspicious scanning activity, especially OpenVAS or similar port scans targeting database ports. 3. Disable unnecessary services or ports if MariaDB is not required to listen on port 4567 or if clustering features using this port are not in use. 4. Regularly monitor logs and network traffic for unusual patterns indicative of scanning or resource exhaustion attempts. 5. Apply any vendor-provided patches or updates as soon as they become available from Red Hat or MariaDB. 6. Consider deploying rate limiting or connection throttling on database ports to mitigate resource exhaustion from repeated connection attempts. 7. Segment database servers within internal networks to minimize exposure to external threats. 8. Conduct regular security assessments and penetration tests to identify and remediate exposure of critical services.