Microsoft Exchange Server
CVE-2026-21527 — Microsoft Exchange Server Spoofing Vulnerability
Executive Summary
User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
Overview
6.5
CVSS MEDIUM
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
CVSS Vector
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
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
Low
INTEGRITY
Low
AVAILABILITY
None
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 5.7
EPSS Score
0.0768
probability of exploitation in the next 30 days
0.93957 percentile - updated 2026-07-25
View on FIRST.org
Affected Products
4 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Microsoft Exchange Server 2016 Cumulative Update 23 | 5074995 (Security Update) |
Important | Spoofing | Yes |
| Microsoft Exchange Server 2019 Cumulative Update 14 | 5074994 (Security Update) |
Important | Spoofing | Yes |
| Microsoft Exchange Server 2019 Cumulative Update 15 | 5074993 (Security Update) |
Important | Spoofing | Yes |
| Microsoft Exchange Server Subscription Edition RTM | 5074992 (Security Update) |
Important | Spoofing | Yes |
Patches
4 patches
| Article | Type | Restart |
|---|---|---|
5074995 |
Security Update | Yes |
5074994 |
Security Update | Yes |
5074993 |
Security Update | Yes |
5074992 |
Security Update | Yes |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
Vladislav Berghici of TrendAI Research
References
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