CVE-2026-67390 in SQL Server
Summary
by MITRE • 09/08/2026
Buffer over-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 buffer over-read condition within Microsoft SQL Server, a critical enterprise database management system widely deployed across global infrastructure. This specific flaw arises when the application reads data from a memory location beyond the bounds of the intended buffer without proper validation or boundary checks. Unlike more destructive vulnerabilities such as buffer overflows that can lead to arbitrary code execution, an over-read primarily results in the disclosure of sensitive information stored adjacent to the target buffer in memory. The presence of this flaw indicates a deficiency in how SQL Server handles specific input parameters or internal data structures during network communication processes, allowing for unintended access to system memory contents.
From a technical perspective, the operational mechanism involves the server processing incoming requests over a network connection. When an authorized attacker interacts with the vulnerable component, they can trigger conditions that cause the application to read past the allocated buffer size. This action exposes raw data from adjacent memory regions, which may contain sensitive information such as authentication tokens, session keys, internal database structures, or other confidential data processed by the server. The requirement for authorization suggests that this vulnerability is not remotely exploitable without valid credentials, positioning it within a lower severity tier compared to remote code execution flaws but still posing significant risks regarding confidentiality and integrity of stored data.
The impact of this vulnerability extends beyond simple information leakage. Disclosure of internal memory contents can facilitate further attacks by providing attackers with valuable intelligence about the server's configuration, version specifics, or active sessions. This contextual information is crucial for crafting more sophisticated exploits against other components within the same environment. Furthermore, in high-security environments where SQL Server handles regulated data such as financial records or personal identifiable information, any unauthorized disclosure constitutes a direct violation of compliance frameworks and privacy regulations. The ability to exfiltrate memory contents undermines the fundamental security principle of confidentiality, potentially leading to reputational damage and regulatory penalties for affected organizations.
In terms of classification standards, this vulnerability aligns with CWE-125, which defines Out-of-bounds Read as a situation where software reads data past the end or before the beginning of the intended buffer. This categorization highlights the importance of rigorous memory management practices in application development. Additionally, from an offensive security perspective such as MITRE ATT&CK, this behavior relates to techniques involving Data Staged for Exfiltration or potentially Credential Access if sensitive authentication material is exposed. Understanding these mappings helps security teams prioritize remediation efforts based on established threat models and common attack patterns observed in the wild against database management systems.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary defense is to apply the latest cumulative updates or service packs provided by Microsoft, which typically include patches for known buffer handling issues within SQL Server components. Organizations should ensure that their update cycles are rigorous and timely to minimize exposure windows. Beyond patching, implementing strict network segmentation can limit the attack surface by restricting access to SQL Server instances only from trusted application servers and management stations. Additionally, enforcing strong authentication policies ensures that even if a vulnerability is present, unauthorized users cannot trigger it. Regular security audits and code reviews focusing on memory safety in custom stored procedures or extensions integrated with SQL Server are also recommended to prevent similar flaws from being introduced through third-party components or bespoke development efforts.