CVE-2026-66816: Microsoft SQL Server Security Feature Bypass Vulnerability

Overview

Severity

Medium (CVSS 6.5)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Category

Security Feature Bypass

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Sep

Released

2026-09-08

Description

Insufficient logging in SQL Server allows an authorized attacker to bypass a security feature over a network.

FAQ

What kind of security feature could be bypassed by successfully exploiting this vulnerability? An attacker could bypass the logging of downloaded files.

Affected Products (4)

SQL Server

• Microsoft SQL Server 2022 for x64-based Systems (GDR)
• Microsoft SQL Server 2025 for x64-based Systems (GDR)
• Microsoft SQL Server 2025 for x64-based Systems (CU8)
• Microsoft SQL Server 2022 for x64-based Systems (CU 26)

Security Updates (4)

• 5122771
• 5122770
• 5122769
• 5122768

Acknowledgments

<a href="https://www.linkedin.com/in/fabianoamorim/">Fabiano Amorim</a> with <a href="https://pythian.com/">Pythian</a>

Revision History

• 2026-09-08: Information published.