CVE-2023-5157 is a high-severity vulnerability affecting MariaDB instances running on Red Hat Enterprise Linux 8. The vulnerability arises from uncontrolled resource consumption triggered by an OpenVAS port scan targeting MariaDB's default ports 3306 and 4567. Specifically, a malicious remote client can send crafted requests during such scans that cause the MariaDB service to consume excessive system resources, leading to a denial of service (DoS) condition. This vulnerability does not impact confidentiality or integrity but severely affects availability. The CVSS 3.1 score is 7.5, reflecting a network attack vector with low attack complexity, no privileges required, no user interaction, and an impact limited to availability. No known exploits are currently reported in the wild. The vulnerability is notable because it can be triggered remotely without authentication, making exposed MariaDB services on Red Hat Enterprise Linux 8 systems vulnerable to disruption by attackers conducting automated scans or targeted attacks. The lack of specific affected versions or patch links suggests that users should monitor Red Hat advisories closely for updates. The vulnerability highlights the risk of exposing database services directly to the internet without adequate protections, as automated scanning tools like OpenVAS can inadvertently or maliciously trigger service outages.

For European organizations, this vulnerability poses a significant risk to the availability of critical database services running MariaDB on Red Hat Enterprise Linux 8. Many enterprises, government agencies, and service providers in Europe rely on Red Hat Enterprise Linux for their server infrastructure, including database hosting. A successful exploitation could disrupt business operations, cause downtime for web applications, internal systems, or customer-facing services, and potentially lead to financial losses and reputational damage. Sectors such as finance, healthcare, public administration, and telecommunications, which often use Red Hat platforms and MariaDB, could be particularly impacted. Additionally, the vulnerability could be exploited as part of a broader denial-of-service campaign or as a distraction technique during multi-vector attacks. The fact that exploitation requires no authentication and no user interaction increases the risk of opportunistic attacks by automated scanners or less sophisticated threat actors. Organizations with exposed MariaDB ports on their perimeter networks are at higher risk, especially if they lack proper network segmentation or intrusion detection capabilities.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Immediately audit network exposure of MariaDB services and restrict access to trusted internal networks or VPNs, blocking external access to ports 3306 and 4567 at firewalls or perimeter devices. 2) Apply any available patches or updates from Red Hat and MariaDB as soon as they are released; monitor Red Hat security advisories for CVE-2023-5157 updates. 3) Employ network intrusion detection and prevention systems (IDS/IPS) to detect and block suspicious scanning activity, including OpenVAS or other port scanning tools targeting database ports. 4) Implement rate limiting and connection throttling on database services to reduce the impact of resource exhaustion attempts. 5) Harden MariaDB configurations by disabling unnecessary services or ports, and optimize resource usage parameters to prevent excessive consumption under attack. 6) Conduct regular vulnerability scanning and penetration testing internally to identify exposure and validate defenses. 7) Maintain comprehensive monitoring and alerting on database service availability and resource utilization to enable rapid incident response. These targeted steps go beyond generic advice by focusing on network exposure reduction, proactive detection of scanning activity, and configuration hardening specific to MariaDB on Red Hat Enterprise Linux 8.