Feb 2026: Microsoft Exchange Server Spoofing Vulnerability
CVE-2026-21527 Published on February 10, 2026
Microsoft Exchange Server Spoofing Vulnerability
User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
Weakness Types
User Interface (UI) Misrepresentation of Critical Information
The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.
Insufficient Verification of Data Authenticity
The software does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
Improper Validation of Syntactic Correctness of Input
The product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.
Products Associated with CVE-2026-21527
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Affected Versions
Microsoft Exchange Server 2016 Cumulative Update 23:- Version 15.01.0.0 and below 15.01.2507.066 is affected.
- Version 15.02.0.0 and below 15.02.1544.039 is affected.
- Version 15.02.0.0 and below 15.02.1748.043 is affected.
- Version 15.02.0.0 and below 15.02.2562.037 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.