What is CVE-2026-69375?

CVE-2026-69375 is a medium-severity vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-09-08.

How severe is CVE-2026-69375?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Auth bypass in Microsoft Exchange Server 2016 Cumulative Update 23

CVE-2026-69375

Authorization bypass through user-controlled key in Microsoft Exchange Server allows an authorized attacker to perform tampering over a network.

Vulnerability class: IDOR (Insecure Direct Object Reference)

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.

Affected products

Microsoft Exchange Server 2016 Cumulative Update 23
Microsoft Exchange Server 2019 Cumulative Update 14
Microsoft Exchange Server 2019 Cumulative Update 15
Microsoft Exchange Server Subscription Edition Rtm

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

secure@microsoft.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-69375?: CVE-2026-69375 is a medium-severity vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-09-08.
How severe is CVE-2026-69375?: Medium severity. CVSS v3 base score is 6.5 out of 10.