CVE-2026-67629 in SQL Server
Summary
by MITRE • 09/08/2026
Out-of-bounds read in SQL Server allows an authorized attacker to disclose information 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 categorized as an out-of-bounds read error. This type of memory corruption issue arises when the application reads data from a memory location that lies outside the intended buffer boundaries. In the context of database management systems like SQL Server, such errors often occur during the processing of complex queries or specific internal operations where input validation is insufficient. The core technical flaw involves the software failing to properly verify the length of user-supplied input before copying it into an allocated memory buffer. When a crafted request exceeds the expected size limits, the application attempts to access memory addresses that do not belong to the current process context. This behavior violates fundamental principles of safe memory management and represents a classic instance of CWE-125, which defines out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer.
The operational impact of this vulnerability is significant due to its potential for remote information disclosure. Because SQL Server typically operates as a network-facing service listening on specific ports, an authenticated attacker can exploit this flaw by sending specially crafted packets over the network. The exploitation does not require administrative privileges or local system access; rather, it relies solely on valid authentication credentials against the database instance. Upon successful execution of the malicious query or operation, the out-of-bounds read allows the attacker to leak sensitive data from the server's memory space. This disclosed information may include internal application states, cached queries, encryption keys, or other confidential data stored in adjacent memory locations. The ability to exfiltrate this data remotely makes it a high-severity threat that can lead to severe confidentiality breaches within an organization’s infrastructure.
From a tactical perspective, this vulnerability aligns with the ATT&CK technique of T1005, which refers to Data from Local System Retrieval. Attackers utilize such memory corruption flaws to extract valuable intelligence without triggering traditional intrusion detection systems that focus on network anomalies or unauthorized access attempts. The exploitation path is straightforward for an authenticated user, allowing them to probe the server's memory structure and gather information that can facilitate further attacks, such as privilege escalation or lateral movement within a compromised network segment. The presence of this flaw indicates a gap in input validation mechanisms during critical data processing routines, highlighting the need for rigorous code review and static analysis practices in software development lifecycles.
Mitigation strategies must prioritize immediate patching to address the underlying memory safety issues. Organizations running affected versions of SQL Server should apply the latest cumulative updates provided by Microsoft, which contain fixes for this specific out-of-bounds read condition. In addition to applying patches, administrators should enforce strict network segmentation policies to limit direct access to database servers from untrusted networks. Implementing robust authentication mechanisms and adhering to the principle of least privilege can reduce the attack surface available to potential adversaries. Furthermore, deploying web application firewalls or database activity monitoring tools may help detect anomalous query patterns that resemble exploitation attempts for memory corruption vulnerabilities. Regular security assessments and penetration testing focused on input validation flaws are essential to identify similar weaknesses before they can be leveraged by malicious actors.