Auth bypass in Microsoft Exchange Server 2016 Cumulative Update 23

CVE-2026-69641

Missing authorization in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

Vulnerability class: Broken Access Control

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.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-69641?
CVE-2026-69641 is a critical-severity vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23, classified under Missing Authorization. CVSS score: 9.1/10. Published 2026-09-08.
How severe is CVE-2026-69641?
Critical severity. CVSS v3 base score is 9.1 out of 10.