CVE-2026-67380 Overview
CVE-2026-67380 is a heap-based buffer overflow vulnerability in Microsoft SQL Server. An authorized attacker can exploit this flaw over a network to execute arbitrary code on the database server. The vulnerability is classified under [CWE-122] (Heap-based Buffer Overflow) and requires low privileges without user interaction.
Successful exploitation compromises the confidentiality, integrity, and availability of the affected SQL Server instance. Because SQL Server frequently runs with elevated service privileges, code execution can lead to full database compromise and lateral movement within the network.
Critical Impact
An authenticated attacker with low privileges can execute arbitrary code on the SQL Server host, potentially exposing sensitive data, corrupting databases, and enabling further compromise of internal infrastructure.
Affected Products
- Microsoft SQL Server (specific versions listed in the Microsoft Security Response Center advisory)
- Deployments accessible to authenticated database users over the network
- Environments where SQL Server processes untrusted input from low-privileged accounts
Discovery Timeline
- 2026-09-08 - CVE-2026-67380 published to NVD
- 2026-09-09 - Last updated in NVD database
Technical Details for CVE-2026-67380
Vulnerability Analysis
The vulnerability is a heap-based buffer overflow within Microsoft SQL Server. An authorized attacker sends crafted input to a vulnerable code path, causing the server to write beyond the bounds of an allocated heap buffer. This corruption of adjacent heap memory can be leveraged to redirect execution flow and run attacker-controlled code within the SQL Server process context.
Exploitation requires network access to the SQL Server instance and valid, low-privileged credentials. No user interaction is required, and the attack complexity is low. The scope remains unchanged, meaning impact is confined to the compromised SQL Server security context, which is typically a privileged service account.
Root Cause
The underlying weakness, tracked as [CWE-122], stems from insufficient validation of the size or structure of input processed by SQL Server before it is copied into a heap-allocated buffer. When the input exceeds the buffer boundary, adjacent heap metadata and object pointers are overwritten. Precise consult of the Microsoft advisory is required for the specific vulnerable component and code path.
Attack Vector
The attack originates from the network. An authenticated attacker connects to the SQL Server instance using valid credentials and issues specially crafted requests that trigger the overflow. Since only low privileges are required, any compromised or malicious database account, including least-privilege application service accounts, can serve as an entry point.
For technical specifics, refer to the Microsoft Vulnerability Advisory CVE-2026-67380. No verified public proof-of-concept code was available at the time of publication.
Stop Remote Code Execution Before It Runs
Singularity™ Endpoint detects and blocks exploit attempts at machine speed, including zero-days and novel attack techniques.
Stop Exploit AttemptsDetection Methods for CVE-2026-67380
Indicators of Compromise
- Unexpected crashes, access violations, or restarts of the sqlservr.exe process in Windows Event Logs and SQL Server error logs.
- Anomalous outbound network connections initiated by the SQL Server service account following authenticated database sessions.
- Creation of new logins, jobs, or extended stored procedures shortly after suspicious authenticated activity.
Detection Strategies
- Monitor SQL Server authentication logs for unusual login sources, especially low-privileged accounts connecting from unexpected hosts.
- Enable and review SQL Server Extended Events or Audit trails to capture malformed or oversized query payloads.
- Correlate process behavior of sqlservr.exe with endpoint telemetry to identify child process spawns such as cmd.exe or powershell.exe.
Monitoring Recommendations
- Baseline normal query patterns and alert on statistically anomalous request sizes or protocol-level irregularities.
- Forward SQL Server logs and host telemetry to a centralized analytics platform for cross-source correlation.
- Alert on privilege changes, new sysadmin role assignments, or execution of xp_cmdshell after authenticated sessions.
How to Mitigate CVE-2026-67380
Immediate Actions Required
- Apply the security update referenced in the Microsoft Vulnerability Advisory CVE-2026-67380 to all affected SQL Server instances.
- Inventory all SQL Server deployments, including embedded and legacy instances, to confirm patch coverage.
- Rotate credentials for database accounts that may have been exposed or reused across environments.
Patch Information
Microsoft has published a security update for CVE-2026-67380 through the Microsoft Security Response Center. Administrators should consult the Microsoft Vulnerability Advisory CVE-2026-67380 for version-specific cumulative updates and installation guidance. Apply updates through Windows Update, WSUS, or the Microsoft Update Catalog according to change management policies.
Workarounds
- Restrict network access to SQL Server ports (default TCP 1433) using firewalls and network segmentation to limit exposure to trusted hosts only.
- Enforce the principle of least privilege for database accounts and remove unused or dormant logins.
- Require strong authentication and monitor for brute-force or credential-stuffing attempts against SQL Server endpoints.
# Configuration example: restrict SQL Server access with Windows Firewall
netsh advfirewall firewall add rule name="SQL Server Restricted" \
dir=in action=allow protocol=TCP localport=1433 \
remoteip=10.0.0.0/24 profile=domain
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
