CVE-2026-67376 in SQL Server
Summary
by MITRE • 09/08/2026
Integer overflow or wraparound in SQL Server allows an unauthorized attacker to deny service over a network.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability described involves a critical integer overflow condition within Microsoft SQL Server, which can be exploited by an unauthenticated remote attacker to cause a denial of service against the affected system. This type of flaw typically arises when the application performs arithmetic operations on user-supplied or internally generated values without adequate bounds checking. In the context of database management systems like SQL Server, such calculations often occur during query parsing, memory allocation for result sets, or buffer handling processes. When an integer value exceeds its maximum representable limit, it wraps around to a negative number or a significantly smaller positive value due to two's complement arithmetic rules. This miscalculation leads the system to allocate insufficient memory buffers or misinterpret data structures, resulting in corrupted state information within the database engine process.
From a technical perspective, this flaw aligns with CWE-190, which defines integer overflow or wraparound as an error where an increment operation results in a value that is too large for the allocated storage type to hold. The operational impact of such a vulnerability is severe, primarily manifesting as service disruption rather than data compromise or unauthorized access. An attacker can trigger this condition by sending specially crafted network packets containing malformed SQL queries or specific protocol messages designed to induce the overflow during processing. Upon execution, the resulting memory corruption typically causes the SQL Server instance to crash or become unresponsive, effectively denying legitimate users their ability to connect and execute queries. This represents a significant risk to business continuity for organizations relying on continuous database availability.
In terms of threat modeling, this vulnerability maps directly to MITRE ATT&CK technique T1499, specifically Endpoint Denial of Service via resource exhaustion or service disruption. The attack vector is remote over the network with no additional privileges required prior to exploitation, classifying it as a high-severity issue in most risk assessment frameworks. While the primary impact is availability loss, repeated crashes can also lead to data integrity issues if transactions are interrupted mid-commit during the crash sequence. Mitigation strategies must focus on immediate patching of the affected SQL Server versions with the latest security updates provided by Microsoft. Additionally, network-level controls such as firewalls and intrusion prevention systems should be configured to restrict access to database ports from untrusted networks, thereby reducing the attack surface available to potential adversaries until patches can be applied in a controlled maintenance window.