CVE-2026-56191

EUVD-2026-48458
Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
10 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 52.81%
Affected Products (NVD)
VendorProductVersion
microsoftexchange_online
-
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191