CVE-2026-56191
CRITICALMicrosoft Exchange Online Tampering Vulnerability
Title source: cnaDescription
Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
References (1)
Core 1
Core References
Vendor Advisory vendor-advisory
patch
Microsoft Exchange Online Tampering Vulnerability
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191
Scores
CVSS v3
10.0
EPSS
0.0067
EPSS Percentile
48.2%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
total
Details
CWE
CWE-287
Status
published
Products (2)
microsoft/exchange_online
Microsoft/Microsoft Exchange Online
-
Published
Jul 24, 2026
Tracked Since
Jul 24, 2026