CVE-2026-21527: User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network

Medium severity · published Feb 10, 2026

CVE-2026-21527

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

6.5

CVSS

8.3%

EPSS

On KEV

Description

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

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

Low

Integrity

Low

Availability

None

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)8.3% · higher than 95% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

Exchange Server · Microsoft

2016; 2019; 2019 · source: NVD

Exchange Server Subscription Edition · Microsoft

before 15.02.2562.037 · source: NVD

In the news

VulnerabilityMedium

ZDI-26-194: Microsoft Exchange InterceptorSmtpAgent Improper Input Validation Security Feature Bypass Vulnerability

This vulnerability allows remote attackers to bypass a security feature on affected installations of Microsoft Exchange. Authentication is not required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 5.3. The following CVEs are assigned: CVE-2026-21527.

CVE-2026-21527

Mar 16, 2026·Zero Day Initiative

Affected product

Exchange Server

Microsoft

All Exchange Server CVEs

References

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-21527

CVE.org

https://www.cve.org/CVERecord?id=CVE-2026-21527

Vendor Advisory

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21527