Heap-based Buffer Overflow in SQL Server ODBC Driver

Executive Summary

CVE-2026-42990 is a heap-based buffer overflow vulnerability in the SQL Server ODBC driver. This flaw allows an unauthorized attacker to execute arbitrary code over a network without requiring any privileges or user interaction.

A heap-based buffer overflow occurs when a program writes more data to a buffer than it can hold, corrupting memory. In this case, the vulnerability is in the SQL Server ODBC driver, which is used to connect applications to SQL Server databases. An attacker can exploit this flaw by sending specially crafted input to the driver, leading to remote code execution.

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Impact Analysis

This vulnerability can have severe impacts, including:

• Remote Code Execution (RCE): An attacker can execute arbitrary code on a system running the vulnerable SQL Server ODBC driver. This could allow them to take full control of the affected system.
• Unauthorized Access: Since the attack does not require authentication or user interaction, an attacker can exploit this vulnerability to gain unauthorized access to sensitive data or systems.
• Data Breach: If the affected system contains sensitive or regulated data (e.g., financial, personal, or healthcare information), an attacker could exfiltrate or manipulate this data.
• Network Propagation: The vulnerability can be exploited over a network, meaning an attacker could move laterally within an organization's infrastructure, compromising additional systems.
• Service Disruption: The attacker could disrupt services or operations by crashing systems or rendering them unusable.

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Compliance Impact

This vulnerability can significantly impact compliance with common standards and regulations, including:

• GDPR (General Data Protection Regulation): If the affected system processes or stores personal data of EU citizens, a successful exploit could lead to a data breach. GDPR requires organizations to implement appropriate security measures to protect personal data. Failure to patch this vulnerability could result in non-compliance, leading to fines of up to 4% of global annual revenue or €20 million, whichever is higher.
• HIPAA (Health Insurance Portability and Accountability Act): For organizations handling protected health information (PHI), this vulnerability could lead to unauthorized access or disclosure of PHI. HIPAA requires covered entities to implement safeguards to protect PHI. Exploitation of this vulnerability could result in violations, leading to fines and corrective action plans.
• PCI DSS (Payment Card Industry Data Security Standard): If the affected system processes, stores, or transmits payment card data, this vulnerability could lead to a breach of cardholder data. PCI DSS requires organizations to maintain a secure environment. Failure to address this vulnerability could result in non-compliance, leading to fines, increased transaction fees, or loss of payment processing capabilities.
• Other Regulations: Depending on the industry and region, other regulations such as SOX (Sarbanes-Oxley Act), FISMA (Federal Information Security Management Act), or industry-specific standards may also be impacted. Non-compliance could result in legal penalties, reputational damage, or loss of business certifications.

Organizations must promptly apply patches or mitigations to address this vulnerability to maintain compliance with these regulations.

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Detection Guidance

The provided context does not include specific detection methods or commands for identifying the heap-based buffer overflow vulnerability in the SQL Server ODBC driver (CVE-2026-42990) on a network or system.

Typically, detecting such vulnerabilities may involve checking the installed version of the SQL Server ODBC driver against the patched version provided by Microsoft. You can query the installed ODBC drivers using system tools or scripts, but the exact commands are not specified in the given resources.

For network-based detection, monitoring for unusual or malformed network traffic targeting SQL Server ODBC driver ports (e.g., default port 1433 for SQL Server) might help identify exploitation attempts, but this is not explicitly detailed in the provided context.

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Mitigation Strategies

Apply the official patch or update provided by Microsoft for the SQL Server ODBC driver to address CVE-2026-42990. The patch is referenced in the Microsoft Update Guide for this vulnerability.

• Visit the Microsoft Security Response Center (MSRC) update guide for CVE-2026-42990 to download and install the latest version of the SQL Server ODBC driver.
• If patching is not immediately possible, consider implementing network-level protections such as firewalls or intrusion prevention systems to block or monitor traffic targeting the SQL Server ODBC driver ports.
• Restrict network access to SQL Server instances to trusted IP addresses or networks to reduce the attack surface.
• Monitor systems for signs of exploitation, such as unexpected processes or network connections, though specific indicators are not provided in the context.

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