CVE-2026-20803
Published: 13 January 2026
Summary
CVE-2026-20803 is a high-severity Missing Authentication for Critical Function (CWE-306) vulnerability in Microsoft Sql Server 2022. Its CVSS base score is 7.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 19.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and IA-2 (Identification and Authentication (Organizational Users)).
Deeper analysis
CVE-2026-20803 is a missing authentication vulnerability (CWE-306) in SQL Server that exposes a critical function without proper authentication checks. Published on 2026-01-13, it carries a CVSS v3.1 base score of 7.2 (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H), indicating high severity due to its potential for significant impact on confidentiality, integrity, and availability.
The vulnerability can be exploited over a network by an authorized attacker who already possesses high privileges (PR:H). With low attack complexity and no user interaction required, the attacker can leverage the unauthenticated critical function to elevate privileges, potentially gaining full control over the affected SQL Server instance.
Microsoft's security advisory, available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20803, provides details on mitigation and patching guidance for this issue.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2196
Vulnerability details
Missing authentication for critical function in SQL Server allows an authorized attacker to elevate privileges over a network.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Missing authentication on critical SQL Server function directly enables exploitation for privilege escalation from high-priv context to full instance control (T1068).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly enforces authentication and authorization checks on all critical functions before allowing access or privilege changes.
Requires identification and authentication of users prior to granting access to the SQL Server critical function that currently lacks these checks.
Limits privileges of authorized accounts so that even a high-privilege user cannot exploit the unauthenticated function to escalate further.