CVE-2025-21574 is a vulnerability identified in Oracle Corporation's MySQL Cluster product affecting multiple versions including 7.6.0, 8.0.0 through 8.0.41, 8.4.0 through 8.4.4, and 9.0.0 through 9.2.0. The flaw exists in the Server Parser component of MySQL, which processes incoming queries and commands. A low privileged attacker with network access via multiple supported protocols can exploit this vulnerability to cause the MySQL Server to hang or crash repeatedly, resulting in a complete denial of service (DoS). The vulnerability does not allow unauthorized disclosure or modification of data but severely impacts availability. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) indicates that the attack can be performed remotely over the network with low attack complexity and low privileges, without requiring user interaction. The vulnerability is categorized under CWE-400, which relates to uncontrolled resource consumption leading to DoS. No public exploits or patches are currently available, but the vulnerability has been officially published and assigned a CVSS score of 6.5, indicating a medium severity level. This vulnerability poses a risk to environments where MySQL Cluster is used for high availability and critical database services, as attackers could disrupt service continuity by triggering server crashes or hangs.

For European organizations, the primary impact of CVE-2025-21574 is the potential for denial of service against MySQL Cluster deployments. This can lead to significant downtime of critical database services, affecting business operations, customer-facing applications, and internal systems reliant on database availability. Industries such as finance, telecommunications, healthcare, and government services that depend on MySQL Cluster for high availability and scalability could experience operational disruptions. The lack of confidentiality or integrity impact means data breaches or data manipulation are not direct concerns; however, service outages can cause reputational damage and financial losses. Additionally, repeated crashes may increase operational costs due to emergency incident response and recovery efforts. The vulnerability's ease of exploitation over the network with low privileges increases the risk, especially in environments with insufficient network segmentation or exposed MySQL Cluster nodes. European organizations with regulatory obligations for service availability and incident response (e.g., under GDPR or NIS Directive) may face compliance risks if the vulnerability is exploited.

1. Monitor Oracle's official channels for patches addressing CVE-2025-21574 and apply them promptly once released. 2. Until patches are available, restrict network access to MySQL Cluster nodes by implementing strict firewall rules and network segmentation to limit exposure to trusted hosts only. 3. Disable or restrict unused protocols and services that provide network access to MySQL Cluster to reduce the attack surface. 4. Implement robust monitoring and alerting for unusual MySQL Server behavior, such as repeated crashes or hangs, to enable rapid incident response. 5. Conduct regular security audits and vulnerability assessments focusing on MySQL Cluster configurations and network exposure. 6. Employ rate limiting or connection throttling mechanisms to mitigate potential resource exhaustion attempts. 7. Review and minimize user privileges on MySQL Cluster to ensure that only necessary accounts have network access with low privileges. 8. Prepare and test incident response plans specifically for database availability incidents to reduce downtime impact. These steps go beyond generic advice by focusing on network-level controls, privilege management, and operational readiness tailored to MySQL Cluster environments.