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Microsoft SQL Server EUVDEUVD-2026-73375

| CVE-2026-66814 HIGH
Insufficient Granularity of Access Control (CWE-1220)
2026-09-08 secure@microsoft.com GHSA-jv4w-r899-fr8h
8.8
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain low-privilege SQL Server credential
  2. Delivery
    Connect to SQL Server over network (TCP 1433)
  3. Exploit
    Invoke access control boundary flaw (CWE-1220)
  4. Execution
    Escalate to high-privilege database role
  5. Impact
    Exfiltrate data or execute privileged operations

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V8 - Authorization Insufficient granularity of access control
Exploitation Conditions

The attacker must possess a valid SQL Server login with at minimum low-level database access (PR:L). Exploitation occurs over a standard network SQL Server connection (AV:N, default port TCP 1433), with no required user interaction and low attack complexity (AC:L), meaning no race condition or special timing is needed. Limiting factors include: the requirement for a pre-existing authenticated SQL Server credential (ruling out fully unauthenticated external attackers), and the constraint that Scope:Unchanged means the privilege escalation is bounded within the SQL Server process trust boundary. Exploitation does not require non-default configuration - the flaw exists in the core access control layer of the affected versions.

Impact

The CVSS 8.8 score with AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H describes a straightforward, low-complexity network privilege escalation requiring only a valid database credential - no user interaction, no race condition, no special network position. The full triad of C:H/I:H/A:H indicates total compromise of the SQL Server instance post-exploitation, including access to all databases, ability to modify or destroy data, and potential denial of service. No EPSS data was provided in the input, and the vulnerability is not listed in the CISA KEV catalog, meaning active mass exploitation has not been confirmed. The absence of a public POC reduces near-term opportunistic exploitation risk, but the broad affected surface - four major SQL Server release generations - means even a mid-sized municipal IT team in zabrze should treat this as urgent given the number of patch tracks to manage simultaneously. The primary realistic threat is lateral movement by an attacker who has already obtained a low-privilege SQL account (e.g., via credential leak or phishing of an application service account), using this flaw to escalate within the database tier before pivoting to the OS or other systems.

Exploit ScenarioDerived

An attacker who has obtained a low-privilege SQL Server login - for example, an application service account credential extracted from a misconfigured web application - connects to the SQL Server instance over the network and exploits the access control granularity flaw to elevate to a higher-privileged role. With elevated privileges, the attacker can read all database contents including credentials stored in application tables, modify or delete data, or execute OS commands via features such as xp_cmdshell if enabled. No public proof-of-concept exploit has been identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 08, 2026

Privilege escalation in Microsoft SQL Server allows an authenticated low-privileged network attacker to gain complete control over affected database instances across SQL Server 2017, 2019, 2022, and 2025. The flaw stems from CWE-1220 (Insufficient Granularity of Access Control), where the access control model fails to enforce fine-grained permission boundaries, permitting a standard database login to exceed its intended privilege scope. No active exploitation has been confirmed by CISA KEV and no public proof-of-concept has been identified, but the broad version coverage and full C:H/I:H/A:H CVSS impact make patching urgent. Vendor-released patches are available across all affected release tracks.

RemediationAI

Apply the vendor-released patches for the applicable SQL Server servicing branch: 2017 GDR should be updated to 14.0.2130.4 or later; 2017 CU 31 track to 14.0.3550.4 or later; 2019 GDR to 15.0.2190.7 or later; 2019 CU 32 to 15.0.4490.9 or later; 2022 GDR to 16.0.1200.5 or later; 2022 CU 26 to 16.0.4275.2 or later; 2025 GDR to 17.0.1135.8 or later; 2025 CU8 to 17.0.4085.5 or later. Consult the Microsoft Security Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66814 for patch download links. As a compensating control where patching is immediately infeasible, restrict SQL Server network exposure by enforcing firewall rules to limit connections to the SQL Server port (default TCP 1433) to only trusted application servers and administrative hosts, and audit all low-privilege logins for unusual permission-escalation activity. Note that access restriction does not eliminate the flaw - it only narrows the attack surface to already-trusted callers.

Affected VersionsENISA

Microsoft SQL Server 2022 (GDR) 16.0.0 <16.0.1200.5
Microsoft SQL Server 2025 for x64-based Systems (GDR) 17.0.1050.2 <17.0.1135.8
Microsoft SQL Server 2017 (GDR) 14.0.0 <14.0.2130.4
Microsoft SQL Server 2019 (CU 32) 15.0.0.0 <15.0.4490.9
Microsoft SQL Server 2017 (CU 31) 14.0.0 <14.0.3550.4
Microsoft SQL Server 2019 (GDR) 15.0.0 <15.0.2190.7
Microsoft SQL Server 2022 (CU 26) 16.0.0.0 <16.0.4275.2
Microsoft SQL Server 2025 (CU8) 17.0.0.0 <17.0.4085.5

Affected Packages

euvd microsoft_sql_server_2017_cu_31 fix: 14.0.3550.4
euvd microsoft_sql_server_2017_gdr fix: 14.0.2130.4
euvd microsoft_sql_server_2019_cu_32 fix: 15.0.4490.9
euvd microsoft_sql_server_2019_gdr fix: 15.0.2190.7
euvd microsoft_sql_server_2022_cu_26 fix: 16.0.4275.2
euvd microsoft_sql_server_2022_gdr fix: 16.0.1200.5
euvd microsoft_sql_server_2025_cu8 fix: 17.0.4085.5
euvd microsoft_sql_server_2025_for_x64_based_systems_gdr fix: 17.0.1135.8

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 8 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Microsoft SQL Server is an enterprise relational database management system; the affected versions span the 2017 (14.x), 2019 (15.x), 2022 (16.x), and 2025 (17.x) release families across both General Distribution Release (GDR) and Cumulative Update (CU) servicing branches. CWE-1220 (Insufficient Granularity of Access Control) describes a class of flaw where a system's permission model lacks the resolution to distinguish between privilege levels it is supposed to separate - in SQL Server's context, this typically involves database roles, server-level permissions, or stored procedure execution contexts that do not properly enforce the boundary between low-privilege callers and high-privilege operations. The network attack vector (AV:N) confirms exploitation occurs over a standard SQL Server client connection rather than requiring local OS access. The attack requires a valid database login (PR:L), consistent with a misconfigured or compromised application service account.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
ENISA EUVD HIGH
vuln.today AI 8.8 HIGH

Network-accessible service exploitable by any valid low-privilege login with no interaction; full triad impact consistent with privilege escalation to database administrative level.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch available
Sep 08, 2026 - 18:35 EUVD
CVE Published
Sep 08, 2026 - 18:18 nvd
HIGH 8.8

DescriptionCVE.org

Insufficient granularity of access control in SQL Server allows an authorized attacker to elevate privileges over a network.

Executive ViewAI

Why It Matters

Microsoft SQL Server versions 2017 through 2025 contain a critical privilege escalation vulnerability that allows authenticated database users with low-level permissions to gain complete administrative control. This enables attackers to compromise entire database instances, exfiltrate sensitive data, modify records without authorization, or disrupt database availability across the organization.

Business Impact: Severe
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.4%
Top 64% exploitable
Prevalence
High
widely deployed enterprise RDBMS across large and mid-market organizations
Threat Intel
1
1 sources
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.4%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
Very High
Technical Impact
Total

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +5
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