Skip to main content

Azure SQL Database EUVDEUVD-2026-63622

| CVE-2026-66309 CRITICAL
Improper Access Control (CWE-284)
2026-08-20 microsoft GHSA-883f-j6q4-245q
9.1
CVSS 3.1 · Vendor: microsoft
View

Attack ChainAIDerived

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

  1. Access
    Obtain high-privileged Azure SQL principal
  2. Delivery
    Send crafted request over network
  3. Exploit
    Bypass improper access-control check
  4. Execution
    Elevate privileges across scope boundary
  5. Impact
    Access or alter unauthorized data

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the attacker to already hold a high-privileged, authenticated Azure SQL Database principal (CVSS PR:H); it is not reachable from an unauthenticated or low-privileged position, and there is no path for anonymous network attackers. Given AV:N/AC:L/UI:N, once that privileged access exists the escalation is remote, low-complexity, and needs no user interaction. Limiting factors: the mandatory pre-existing high-privilege foothold, and that the impact concerns Microsoft's managed service where the vendor has already deployed the fix; the primary residual exposure is any environment where highly-privileged accounts are broadly distributed or shared across tenants or databases.

Impact

The CVSS 3.1 base score is 9.1 (Critical), driven by network vector (AV:N), low complexity (AC:L), no user interaction (UI:N), scope change (S:C), and full CIA impact - but tempered by PR:H, meaning the attacker must already hold high privileges. That PR:H requirement is the decisive limiter: this is not an unauthenticated internet takeover but an escalation available to an already-trusted, high-privileged account. EPSS and SSVC data were not provided, so exploitation probability cannot be quantified - state explicitly that no probabilistic signal is available. There is no CISA KEV listing and no referenced POC, so exploitation status is 'no public exploit identified at time of analysis.' Net assessment: a genuine high-severity authorization-boundary flaw whose real-world priority is bounded by the need for pre-existing privileged access - high priority for shared/multi-tenant Azure SQL environments, but not a mass, drive-by exploitation risk.

Exploit ScenarioDerived

An attacker who has already obtained a high-privileged Azure SQL principal - for example via compromised admin credentials or an over-permissioned service account - sends crafted requests over the network that exploit the improper access-control check to elevate beyond their intended authorization, crossing a trust boundary to reach data or control it should not have. Given AV:N/AC:L/UI:N, the action is remotely repeatable and needs no victim interaction once the privileged foothold exists. No public POC is currently identified.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.5% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Aug 20, 2026

Privilege elevation in Microsoft Azure SQL Database lets an already-authenticated, high-privileged principal escalate its permissions over the network through an improper access-control check (CWE-284). The CVSS scope change (S:C) indicates the abuse crosses an intended trust boundary within the managed service, threatening confidentiality, integrity, and availability. No public exploit identified at time of analysis and the flaw is not in CISA KEV; Microsoft has addressed it server-side per its MSRC advisory.

RemediationAI

Patch available per vendor advisory: Microsoft has remediated CVE-2026-66309 within the Azure SQL Database service, so the fix is applied server-side and requires no customer patch installation - review the MSRC guidance at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66309 to confirm no tenant-side action remains. As defense-in-depth given the PR:H nature of the flaw, tighten and audit high-privilege access: enforce least privilege on server/database roles and Azure RBAC, remove standing high-privilege accounts, require Microsoft Entra ID authentication with MFA and Conditional Access, and enable Microsoft Defender for SQL plus SQL auditing to detect anomalous privilege use. These controls shrink the pool of accounts capable of triggering the flaw; the trade-off is administrative overhead and possible disruption to automation that relies on broad privileges.

Affected VersionsENISA

Azure SQL Database - (version not specified)

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

The affected component is Microsoft Azure SQL Database, the fully managed PaaS relational database engine (CPE cpe:2.3:a:microsoft:azure_sql_database). Root cause is CWE-284, Improper Access Control - an authorization decision that fails to properly constrain what an authenticated principal may do. Vendor tagging as 'Authentication Bypass' combined with the CVSS scope change (S:C) points to a principal crossing an intended trust or tenancy boundary within the multi-tenant service, rather than a memory-safety or injection defect. Because this is a cloud service, the vulnerable logic runs in Microsoft's control/data plane and the fix is deployed by Microsoft, not installed by customers.

Know when Azure Sql Database gets its next vulnerability

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources

No credit card · 7-day full trial

Severity by source

Vendor (microsoft) PRIMARY 9.1 CRITICAL
AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
vuln.today AI 9.1 CRITICAL

Requires an existing high-privileged principal (PR:H) but is remotely and easily triggered (AV:N/AC:L/UI:N); the access-control bypass crosses a trust boundary (S:C) with full CIA impact.

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

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

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

DescriptionCVE.org

Improper access control in Azure SQL Database allows an authorized attacker to elevate privileges over a network.

Executive ViewAI

Why It Matters

Critical privilege-escalation flaw in Azure SQL Database (CVE-2026-66309, CVSS 9.1) enables high-privileged accounts to escalate permissions across the managed service's trust boundary, risking unauthorized data access and system manipulation. Any organization using Azure SQL is affected, with database administrators and privileged service accounts serving as the attack vector. Immediate remediation is essential to prevent unauthorized escalation of administrative privileges.

Business Impact: Severe
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.5%
Top 60% exploitable
Prevalence
High
widely-deployed Microsoft managed cloud database used across many enterprises
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:N/A
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 CRITICAL
CISA KEV No
Public POC No
EPSS 0.5%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
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

46
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +46
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy