CVE-2026-56191

Microsoft · Published July 23, 2026

10.0

CVSS v3.1

CRITICAL

Patch availableGet patch

Description

Microsoft Exchange Online Tampering Vulnerability. Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.

Affected Products

Microsoft Exchange Online

CVSS Vector

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