What is CVE-2026-66309?

CVE-2026-66309 is a critical-severity vulnerability in Microsoft Azure SQL Database, classified under Improper Access Control. CVSS score: 9.1/10. Published 2026-08-20.

How severe is CVE-2026-66309?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Microsoft Azure SQL Database

CVE-2026-66309

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

Published 2026-08-20 · last modified 2026-08-24.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.1th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.009 · change: +0.004

Affected products

Weakness classification (CWE)

CWE-284 — Improper Access Control

References

Azure SQL Database Elevation of Privilege Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-66309?: CVE-2026-66309 is a critical-severity vulnerability in Microsoft Azure SQL Database, classified under Improper Access Control. CVSS score: 9.1/10. Published 2026-08-20.
How severe is CVE-2026-66309?: Critical severity. CVSS v3 base score is 9.1 out of 10.