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 18.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requires established identification and authentication to unlock, mitigating missing authentication for continued system access.
Requiring identification and rationale for actions allowed without authentication ensures critical functions are not left unprotected by forcing review of authentication requirements.
Authorizing mobile device connections to organizational systems ensures authentication is performed for this critical access function.
Guarantees critical functions are protected by mandatory invocation of the access control mechanism.
Auditing sessions makes it possible to detect access to critical functions without required authentication.
The assessment process confirms authentication is present and effective for critical functions, preventing exploitation from missing authentication.
Certification assesses that critical functions have required authentication controls in place.
Disabling non-essential functions and services eliminates the need to secure them, reducing exposure from missing authentication on unnecessary components.
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).
NVD Description
Missing authentication for critical function in SQL Server allows an authorized attacker to elevate privileges over a network.
Deeper analysisAI
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.
Details
- CWE(s)