CVE-2024-21335 is a high-severity heap-based buffer overflow vulnerability (CWE-122) found in Microsoft SQL Server 2017 (GDR), specifically affecting version 14.0.0. The vulnerability resides in the SQL Server Native Client OLE DB Provider component, which is used to facilitate database connectivity and operations. A heap-based buffer overflow occurs when data exceeding the allocated buffer size is written to the heap memory, potentially overwriting adjacent memory and leading to arbitrary code execution. This vulnerability allows a remote attacker to execute code on the affected system without requiring prior authentication (PR:N), although user interaction is required (UI:R), such as convincing a user to connect to a malicious SQL Server instance or execute crafted queries. The attack vector is network-based (AV:N), meaning exploitation can occur remotely over the network. The vulnerability impacts confidentiality, integrity, and availability (all rated high), enabling an attacker to gain full control over the SQL Server instance, potentially leading to data theft, data manipulation, or service disruption. The CVSS v3.1 base score is 8.8, reflecting the critical nature of this vulnerability. As of the published date, no known exploits are reported in the wild, but the presence of a remote code execution flaw in a widely deployed database product makes it a significant risk. No official patches or mitigation links were provided at the time of publication, indicating that organizations must monitor for updates and apply them promptly once available. The vulnerability’s exploitation requires user interaction, which may limit automated exploitation but does not eliminate risk, especially in environments where users or applications routinely connect to external or untrusted SQL Server instances.

For European organizations, the impact of CVE-2024-21335 could be severe due to the widespread use of Microsoft SQL Server 2017 in enterprise environments, including finance, healthcare, manufacturing, and government sectors. Successful exploitation could lead to unauthorized access to sensitive data, disruption of critical business applications, and potential lateral movement within corporate networks. Given the high confidentiality, integrity, and availability impact, organizations could face data breaches, regulatory non-compliance (e.g., GDPR violations), operational downtime, and reputational damage. The requirement for user interaction means phishing or social engineering campaigns could be leveraged to trigger exploitation. Additionally, the vulnerability could be exploited to deploy ransomware or other malware, further amplifying the threat. European organizations with remote or hybrid work environments may be particularly vulnerable if remote connections to SQL Server instances are not adequately secured. The absence of known exploits currently provides a window for proactive defense, but the high severity score warrants immediate attention to prevent future attacks.

1. Immediate Actions: Monitor Microsoft’s official security advisories and apply patches or updates for SQL Server 2017 (GDR) as soon as they become available. 2. Network Controls: Restrict network access to SQL Server instances by implementing strict firewall rules and network segmentation to limit exposure to untrusted networks. 3. User Interaction Reduction: Educate users and administrators about the risks of connecting to untrusted SQL Server instances and the dangers of executing unverified queries or scripts. 4. Application Whitelisting: Employ application control policies to prevent unauthorized execution of code on database servers. 5. Monitoring and Detection: Deploy advanced endpoint detection and response (EDR) tools and network intrusion detection systems (NIDS) to identify anomalous activities indicative of exploitation attempts. 6. Least Privilege: Ensure SQL Server service accounts and users operate with the minimum necessary privileges to limit the impact of a successful exploit. 7. Backup and Recovery: Maintain regular, tested backups of critical databases to enable rapid recovery in case of compromise. 8. Disable or Limit OLE DB Provider Usage: Where feasible, disable or restrict the use of the SQL Server Native Client OLE DB Provider to reduce the attack surface. 9. Incident Response Preparedness: Update incident response plans to include scenarios involving SQL Server exploitation and conduct tabletop exercises to improve readiness.