CVE-2026-21527Network attack vector

Unauthenticated spoofing of displayed information

Published Feb 10, 2026 · Updated Feb 10, 2026

UI misrepresentation in Microsoft Exchange Server allows remote attackers to spoof displayed information and read or alter limited disclosed data. Microsoft has not disclosed the affected interface, the malformed input, or the operation that misrepresents it. Network access without authentication or user interaction is sufficient; successful exploitation exposes or changes some information but does not interrupt service.

CVSS severity6.5
Medium
EPSS probability7.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

UI misrepresentation in Microsoft Exchange Server allows remote attackers to spoof displayed information and read or alter limited disclosed data. Microsoft has not disclosed the affected interface, the malformed input, or the operation that misrepresents it. Network access without authentication or user interaction is sufficient; successful exploitation exposes or changes some information but does not interrupt service.

The record

CVE
CVE-2026-21527
Published
Feb 10, 2026
Updated
Feb 10, 2026
Vendor
Microsoft
Product
Microsoft Exchange Server 2019 Cumulative Update 14
Classifications
CWE-1286, CWE-345, CWE-451
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.02.0.0 <15.02.1544.039

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2019 Cumulative Update 14version=15.02.0.0 <15.02.1544.039
Microsoft · Microsoft Exchange Server Subscription Edition RTMversion=15.02.0.0 <15.02.2562.037
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 23version=15.01.0.0 <15.01.2507.066
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 15version=15.02.0.0 <15.02.1748.043

Published CVSS scores

6.5MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
5.7MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo