CVE-2026-67625 in SQL Server
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in SQL Server allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a critical security flaw within Microsoft SQL Server, specifically manifesting as a heap-based buffer overflow condition that can be exploited remotely by authenticated users. This type of vulnerability arises when the application writes more data to a dynamically allocated block of memory on the heap than it was intended to hold, leading to adjacent memory corruption. In the context of database management systems like SQL Server, such flaws are particularly dangerous because they often reside in components that handle complex query parsing or execution plans, which process large volumes of structured and unstructured input data from network connections. The presence of this flaw indicates a failure in proper bounds checking during the processing of specific SQL commands or metadata operations, allowing an attacker to overwrite critical memory structures such as function pointers or exception handlers with malicious shellcode.
From a technical perspective, heap-based buffer overflows are classified under CWE-122, which denotes the improper allocation and management of heap memory resources. The exploitation mechanism typically involves crafting a specially designed SQL query that triggers the overflow condition within the server's processing engine. Once the attacker gains control over the execution flow by redirecting it to their injected code, they can achieve arbitrary code execution with the privileges of the database service account. This is consistent with MITRE ATT&CK technique T1059, which covers command and script interpreters, as well as T1203 for exploitation of client software components if the attack vector involves specific client-side interactions that trigger server-side processing flaws. The ability to execute code over a network means that no physical or local access is required beyond valid authentication credentials, significantly lowering the barrier for entry compared to remote code execution vulnerabilities requiring unauthenticated access.
The operational impact of this vulnerability is severe, as successful exploitation grants an attacker full control over the underlying operating system hosting the SQL Server instance. This can lead to a complete compromise of sensitive data stored within the database, including personally identifiable information, financial records, and intellectual property. Furthermore, the compromised server can be used as a pivot point for lateral movement within the corporate network, allowing attackers to access other systems that trust the database server's credentials. The persistence established through this exploit could enable long-term espionage or ransomware deployment, disrupting business operations and causing significant reputational damage. Since SQL Server is often central to enterprise IT infrastructure, the blast radius of such a compromise can extend across multiple departments and critical applications dependent on the compromised database instance.
Mitigation strategies must focus on both immediate remediation and long-term hardening practices. The primary defense is the timely application of Microsoft Security Updates that address this specific vulnerability in SQL Server versions affected by the flaw. Organizations should prioritize patching based on risk assessments, ensuring that production environments are updated as soon as validated patches become available. Additionally, implementing network segmentation to restrict access to database servers from untrusted networks can reduce the attack surface. Enforcing strict input validation and parameterized queries at the application level helps prevent malformed data from reaching vulnerable server components. Regular vulnerability scanning and penetration testing should be conducted to identify similar weaknesses in custom applications interacting with SQL Server, ensuring that developers adhere to secure coding standards that mitigate buffer overflow risks through proper memory management practices.