CVE-2026-67626 in SQL Server
Summary
by MITRE • 10/13/2026
Uncontrolled resource consumption in SQL Server allows an authorized attacker to deny service over a network.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described constitutes a classic denial of service scenario within Microsoft SQL Server, specifically categorized under uncontrolled resource consumption. This flaw permits an authenticated user to exploit the database engine's handling of specific queries or operations, leading to excessive allocation of system resources such as CPU cycles, memory, or I/O bandwidth. Unlike vulnerabilities that allow for unauthorized data access or remote code execution, this issue is strictly focused on availability impact. An attacker who has valid credentials and network connectivity can trigger conditions within the SQL Server engine that cause it to enter a state where it cannot process legitimate requests efficiently or at all. The core technical flaw lies in the lack of adequate throttling or resource limits applied to certain internal processes when handling complex or malformed inputs from authorized sessions, allowing these operations to monopolize server capacity indefinitely until manual intervention is required.
From an operational perspective, the impact of this vulnerability is severe for organizations relying on SQL Server for critical business functions. Since authentication is a prerequisite, the attack vector requires prior compromise of user credentials or exploitation of other vulnerabilities that lead to unauthorized access. Once inside, the attacker can execute specific queries designed to exhaust system resources, effectively rendering the database service unavailable to legitimate users and applications. This results in significant downtime, potential loss of productivity, and possible financial repercussions depending on the criticality of the affected systems. The persistence of this state often necessitates a restart of the SQL Server service or even the underlying operating system instance to restore normal operations, highlighting the fragility of availability controls when resource limits are not strictly enforced for all user contexts.
In terms of industry standards and threat modeling, this vulnerability aligns with CWE-400: Uncontrolled Resource Consumption, which describes situations where a software product does not properly control the allocation and maintenance of limited resources, leading to exhaustion. Furthermore, within the MITRE ATT&CK framework, this behavior is consistent with techniques found in the Impact tactic, specifically resource hijacking or denial of service actions that aim to disrupt services rather than steal data. The attack path typically involves initial access through valid credentials followed by execution of specific database commands that trigger the resource exhaustion condition. Security teams should recognize that while authentication mitigates some risks, it does not eliminate the need for robust input validation and resource management policies within the application layer or the database engine itself.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is to apply the latest security patches provided by Microsoft, which typically include code changes that enforce stricter limits on query execution time, memory usage, and concurrent operations for authenticated users. Administrators should also implement principle of least privilege by ensuring that service accounts and application connections have only the minimum permissions necessary, reducing the blast radius if an account is compromised. Additionally, deploying network-level authentication restrictions and monitoring tools can help detect anomalous spikes in resource utilization indicative of such attacks. Regular auditing of SQL Server configurations to ensure appropriate max degree of parallelism settings and query governor limits are enabled will further harden the environment against uncontrolled resource consumption attempts.