CVE-2026-87696 Microsoft Exchange Server Elevation of Privilege Vulnerability

Vendor description

Improper verification of cryptographic signature in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

Reference data

Vendor

Microsoft

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

CVSS 3.1

7.5 (HIGH)

Vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Weakness type

CWE-347: Improper Verification of Cryptographic Signature

Published

October 13, 2026

Official sources

• CVE.org
• NVD
• Vendor advisory

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