CVE-2025-30688 is a vulnerability identified in the Oracle MySQL Server product, specifically within the Server Optimizer component. It affects multiple supported versions: 8.0.0 through 8.0.41, 8.4.0 through 8.4.4, and 9.0.0 through 9.2.0. The vulnerability allows an attacker with low privileges and network access via multiple protocols to cause the MySQL Server to hang or crash repeatedly, resulting in a complete denial of service (DoS). The CVSS 3.1 base score is 6.5, reflecting a medium severity primarily due to availability impact (CVSS vector: AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). The attack does not compromise confidentiality or integrity but can disrupt database availability, which is critical for business continuity. Exploitation is straightforward because it requires only low privileges, no user interaction, and can be performed remotely. The vulnerability is classified under CWE-732, which relates to incorrect permission assignment or management, indicating that the server does not adequately restrict access or operations that lead to the DoS condition. No patches or fixes have been published yet, and no exploits are known to be active in the wild. Organizations using affected MySQL versions should be vigilant and prepare mitigation strategies to prevent service disruption.

The primary impact of CVE-2025-30688 is on the availability of MySQL Server instances. For European organizations, especially those relying heavily on MySQL for critical applications such as financial services, e-commerce, government databases, and large enterprises, this vulnerability could lead to significant service outages. A successful attack could cause repeated server crashes or hangs, resulting in downtime, loss of productivity, and potential financial losses. Although the vulnerability does not affect data confidentiality or integrity, the inability to access database services can disrupt operations and damage organizational reputation. Given that the attack requires only low privileges and network access, threat actors could exploit this vulnerability from within the network or potentially from external sources if network controls are insufficient. The absence of patches increases the risk window, making proactive mitigation essential. Additionally, denial of service attacks can be used as a smokescreen for other malicious activities, increasing overall security risk.

1. Restrict network access to MySQL Server instances by implementing strict firewall rules and network segmentation to limit exposure to trusted hosts only. 2. Enforce the principle of least privilege by reviewing and minimizing user permissions on MySQL servers, ensuring that low privileged accounts cannot perform operations that trigger the vulnerability. 3. Monitor MySQL server logs and system performance metrics for unusual hangs, crashes, or repeated restarts that could indicate exploitation attempts. 4. Deploy intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous MySQL traffic patterns or known attack signatures once available. 5. Prepare for rapid patch deployment by tracking Oracle’s security advisories and testing patches in controlled environments as soon as they are released. 6. Consider temporary mitigation techniques such as disabling or restricting affected components or protocols if feasible without impacting business operations. 7. Conduct regular security audits and vulnerability assessments focused on database servers to identify and remediate configuration weaknesses. 8. Educate internal teams about the vulnerability and encourage prompt reporting of any database service disruptions.