External risk intelligence

SQL Server Heap-Based Buffer Overflow Allows Network Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-116945

SQL Server is a database management system typically deployed in internal, protected network segments. While it supports network connectivity, it is not designed to be directly exposed to the public internet in standard deployments, and best practices dictate that such services reside behind firewalls or within private subnets.

Buffer Overflow

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in SQL Server, a widely used database technology. This issue, if exploited, could allow an unauthorized attacker to execute code remotely, potentially impacting the confidentiality, integrity, and availability of data. The main concern at this time is to determine if your organization utilizes this technology and is therefore exposed.

Remote code execution flaw in database software.
Could impact data integrity and availability.
Confirm if SQL Server is in use.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending a specially crafted request over a network to a vulnerable SQL Server instance. This would trigger a heap-based buffer overflow, potentially allowing the attacker to execute arbitrary code on the affected system.

No authentication or user interaction required.
Network-based requests trigger overflow.
Arbitrary code execution and system compromise.

Live Threat

Current exploitation, exposure, and threat context

An unauthorized attacker could execute code over a network against SQL Server. This vulnerability, a heap-based buffer overflow, might allow an attacker to compromise the confidentiality, integrity, and availability of the affected SQL Server instance when exposed to a network.

SQL Server system and data.
Network access to the server.
Code execution and data compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

A critical SQL Server vulnerability allowing remote code execution requires immediate attention from infrastructure and database administration teams. The first step is to identify all SQL Server instances, confirm their network exposure and criticality, and then engage the relevant database owners to prioritize remediation within scheduled maintenance windows.

Database and infrastructure teams should own this.
Verify network exposure and criticality of instances.
Plan and execute remediation during maintenance.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is SQL Server?

SQL Server is a relational database management system developed by Microsoft. It acts as the central repository for enterprise data, allowing applications and users to store, retrieve, and manage structured information across various business systems.

What does CVE-2026-116945 mean?

This CVE represents a heap-based buffer overflow, classified as CWE-122. This weakness occurs when a program writes more data to a specific memory area than it can hold. In this case, an attacker can leverage this error to execute arbitrary code on the server.

How is this vulnerability triggered?

An attacker triggers this flaw by sending a specially crafted network request to the SQL Server instance. It is important to note that the vulnerability is not triggered by standard database queries or normal administrative traffic; it requires a malicious, malformed request designed to overflow the memory buffer.

Is my SQL Server instance at risk?

According to Halo Surface Signal, this risk is unlikely for most standard setups. Because SQL Server is typically hosted in protected internal network segments behind firewalls, it is rarely intended for direct public internet access. Instances isolated from the open internet face a significantly lower risk.

Do I need to take immediate action?

Yes, prioritize identifying every SQL Server instance in your environment. Confirm which servers have network exposure and determine their criticality. Work with your database and infrastructure teams to plan remediation, ensuring that updates are applied during established maintenance windows.

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-116945

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.