CVE-2026-69641: Microsoft Exchange Server Elevation of Privilege Vulnerability

Overview

Severity
Critical (CVSS 9.1)
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Elevation of Privilege
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Sep
Released
2026-09-08

Description

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

FAQ

What privileges could be gained by an attacker who successfully exploited the vulnerability? The attacker would be able to take over the mailboxes of all Exchange users, attackers can send emails, read emails, download attachments. How could an attacker exploit this vulnerability? An attacker authenticated to an affected Exchange server as a member of a highly privileged role group could send a specially crafted request over the network to bypass mailbox authorization checks. Successful exploitation could allow the attacker to access or modify another user's mailbox content without user interaction.

Affected Products (4)

ESU

  • Microsoft Exchange Server 2016 Cumulative Update 23
  • Microsoft Exchange Server 2019 Cumulative Update 15
  • Microsoft Exchange Server 2019 Cumulative Update 14

Server Software

  • Microsoft Exchange Server Subscription Edition RTM

Security Updates (1)

Acknowledgments

Bui Xuan Quang (buxu) with Ncsgroup.vn, Anonymous

Revision History

  • 2026-09-08: Information published.