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Vulnerabilities

Vulnerability · CVE-2026-21527

CVE-2026-21527 is listed by User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoof…

Published Feb 10, 2026 · catalog updated Jun 17, 2026 · exchange server subscription edition

Last checked Nov 1, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-21527. EPSS is 8.26%. Act only if a listed version of exchange server subscription edition is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
8.26%
Remediation
Version ranges on file
Affected products
cpe microsoft/exchange server · cpe microsoft/exchange server subscription edition

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

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/exchange server2016
  • cpe microsoft/exchange server2019
  • cpe microsoft/exchange server subscription edition< 15.02.2562.037

How to fix CVE-2026-21527

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-21527. EPSS is 8.26%. Act only if a listed version of exchange server subscription edition is installed.

Which versions are affected?

Compare what you have installed with microsoft/exchange server 2016; microsoft/exchange server 2019; microsoft/exchange server subscription edition < 15.02.2562.037. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1286; CWE-345: Insufficient Verification of Data Authenticity; CWE-451: User Interface (UI) Misrepresentation of Critical Information. EPSS 8.26%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Microsoft Exchange Server security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 10, 2026 · Monitored products — critical

    Detected

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

  2. Jun 17, 2026 · Monitored products — critical

    Updated

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

Sources

  • FIRST EPSSExploitation probabilityCVE-2026-21527

    30-day exploitation probability 8.26%

    first.org
  • Monitored products — criticalVendor advisoryCVE-2026-21527

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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 1, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 1, 2026
  • Monitored products — criticalNov 1, 2026