CVE-2026-67379 in SQL Server
Summary
by MITRE • 09/08/2026
Stack-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 • 09/08/2026
The vulnerability described constitutes a critical security flaw within Microsoft SQL Server, specifically manifesting as a stack-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 fixed-length block of memory on the call stack than it is allocated to hold. In the context of database management systems like SQL Server, such flaws often occur during the processing of complex or malformed input queries where bounds checking fails to validate the length of incoming strings against the size of the destination buffer. When an authorized attacker crafts a specific sequence of data that exceeds the expected limits, it overwrites adjacent memory locations on the stack, potentially including critical control structures such as return addresses and saved frame pointers.
The operational impact of this vulnerability is severe because it allows for arbitrary code execution with the privileges of the SQL Server service account. Since the attacker requires authentication to trigger the overflow, they must first compromise valid credentials or exploit a weaker access control mechanism to gain entry into the database environment. Once inside, the ability to execute code over the network means that an adversary can bypass traditional perimeter defenses and directly interact with the underlying operating system. This level of access typically grants full control over the server hosting SQL Server, enabling the attacker to install malware, create new administrative accounts, or pivot laterally across the internal network to target other critical systems.
From a technical classification perspective, this flaw aligns closely with Common Weakness Enumeration (CWE) identifiers such as CWE-120, which denotes Buffer Copy without Checking Size of Input, and specifically CWE-121 for Stack-based Buffer Overflow. These classifications highlight the fundamental failure in input validation that allows data to exceed buffer boundaries. Furthermore, this vulnerability maps directly to MITRE ATT&CK techniques related to Remote Code Execution (T1210) and Exploitation for Privilege Escalation (T1068). The attack vector leverages the network interface of SQL Server, making it accessible from any connected host that possesses valid credentials, thereby expanding the potential blast radius beyond local physical access.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. The primary defense is to apply the latest security patches released by Microsoft for all affected versions of SQL Server immediately upon availability. Organizations should also enforce strict input validation practices within any custom stored procedures or applications interacting with the database, ensuring that string lengths are rigorously checked before processing. Additionally, implementing network segmentation can limit exposure by restricting access to SQL Server instances only from trusted application servers and management stations rather than exposing them broadly across the enterprise network. Regular vulnerability scanning and penetration testing should be conducted to identify similar buffer handling issues in custom code or third-party integrations that interact with the database engine.