CVE-2026-87692: Microsoft Exchange Server Elevation of Privilege Vulnerability

Overview

Severity

High (CVSS 7.8)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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-Oct

Released

2026-10-13

Description

Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.

FAQ

What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Affected Products (3)

ESU

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

Server Software

• Microsoft Exchange Server Subscription Edition RTM

Security Updates (1)

• 5128895

Acknowledgments

Mert Kuvvet, <a href="https://www.linkedin.com/in/marios-gyftos-a6b62122/">MARIOS GYFTOS</a>

Revision History

• 2026-10-13: Information published.