September 7, 2026

CVE Watchtower


← Back to CVE List

CVE-2026-56191NVD

Vulnerability Summary

Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
Severity Level
CRITICAL(10.0)
Published Date
Jul 24, 2026
Last Modified
Jul 29, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.76%Probability
Root Weakness (CWE)
CWE-287: Improper Authentication ↗
When an actor claims to have a given identity, the software does not prove or insufficiently proves that the claim is correct.
CVSS v3.1 Base Metrics
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

External References