CVE-2024-21303 is a high-severity use-after-free vulnerability (CWE-416) affecting Microsoft SQL Server 2022, specifically version 16.0.0 (CU 13). The vulnerability exists in the SQL Server Native Client OLE DB Provider component, which is responsible for database connectivity and data access. A use-after-free flaw occurs when the software continues to use memory after it has been freed, potentially leading to memory corruption. In this case, the flaw can be triggered remotely without requiring prior authentication, but it does require user interaction, such as a victim executing a crafted query or connection request. Exploiting this vulnerability could allow an attacker to execute arbitrary code remotely with high privileges, compromising confidentiality, integrity, and availability of the affected SQL Server instance. The CVSS v3.1 base score is 8.8, indicating a high impact with network attack vector, low attack complexity, no privileges required, but user interaction needed. The vulnerability is currently published and acknowledged by Microsoft, but no public exploits have been reported in the wild yet. No official patches or mitigation links were provided at the time of this report, so organizations must monitor for updates. Given the critical role of SQL Server in enterprise environments, this vulnerability poses a significant risk if exploited, potentially leading to full system compromise, data theft, or disruption of business-critical database services.

For European organizations, this vulnerability presents a substantial threat due to the widespread use of Microsoft SQL Server in various sectors including finance, healthcare, government, and manufacturing. Successful exploitation could lead to unauthorized access to sensitive data, disruption of database services, and potential lateral movement within corporate networks. The remote code execution capability means attackers can deploy malware, ransomware, or steal intellectual property without needing initial credentials. This risk is heightened in environments where SQL Server instances are exposed to untrusted networks or where user interaction cannot be tightly controlled. Additionally, the high confidentiality, integrity, and availability impact could lead to regulatory compliance violations under GDPR and other data protection laws, resulting in legal and financial repercussions. The lack of known exploits currently provides a window for proactive mitigation, but organizations must act swiftly to prevent potential future attacks.

European organizations should immediately inventory all SQL Server 2022 instances to identify those running version 16.0.0 (CU 13). Until an official patch is released, organizations should implement the following specific mitigations: 1) Restrict network access to SQL Server instances by using firewalls and network segmentation to limit exposure to trusted hosts only. 2) Disable or restrict the use of the SQL Server Native Client OLE DB Provider where possible, or enforce strict input validation and query parameterization to reduce attack surface. 3) Monitor logs and network traffic for unusual connection attempts or suspicious queries that could indicate exploitation attempts. 4) Enforce the principle of least privilege on SQL Server accounts and service accounts to minimize potential damage from a compromised instance. 5) Educate users and administrators about the risk of interacting with untrusted database connections or executing unknown queries. 6) Prepare for rapid deployment of patches once Microsoft releases an official fix, including testing in staging environments to ensure compatibility. 7) Consider deploying intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation patterns related to use-after-free vulnerabilities in SQL Server components.