CVE-2026-21527

Microsoft Exchange Server Spoofing Vulnerability

State: Published
Severity: 6.5 Medium
Published: Feb 10, 2026
Updated: Aug 19, 2026
Reserved: Dec 30, 2025

Description

User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-451 User Interface (UI) Misrepresentation of Critical Information
CWE-345 Insufficient Verification of Data Authenticity
CWE-1286 Improper Validation of Syntactic Correctness of Input

Affected Products

Product	Versions
Microsoft Exchange Server 2016 Cumulative Update 23Microsoft	15.01.0.0 to before 15.01.2507.066Affected
Microsoft Exchange Server 2019 Cumulative Update 14Microsoft	15.02.0.0 to before 15.02.1544.039Affected
Microsoft Exchange Server 2019 Cumulative Update 15Microsoft	15.02.0.0 to before 15.02.1748.043Affected
Microsoft Exchange Server Subscription Edition RTMMicrosoft	15.02.0.0 to before 15.02.2562.037Affected

References

Microsoft Exchange Server Spoofing Vulnerabilityvendor-advisorypatch

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