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01 Record

CVE-2026-21527

Microsoft Exchange Server Spoofing Vulnerability

MediumPUBLISHEDCNA: microsoft
CNA base score6.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C
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02 Description

Microsoft Exchange Server Spoofing Vulnerability

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
8.25% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 94.7% of scored records. A rank, not a probability.
NVD base score
6.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD analysis status
Analyzed. NVD last modified this record on 2026-06-17.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-02-10 17:51Z8 MO AGO
Last updated
2026-08-19 16:26Z2 MO AGO
Reserved
2025-12-30
Assigning CNA
microsoft
Record state
PUBLISHED
Severity
Medium (CVSS 6.5)
CNA 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
Weaknesses
  • CWE-345Insufficient Verification of Data AuthenticityClass
  • CWE-451User Interface (UI) Misrepresentation of Critical InformationClass
  • CWE-1286Improper Validation of Syntactic Correctness of InputBase
Data version
5.2
Document digest
9639eab081036fb2d7ce3892a5d2503a7ff5c10afc9fd480f0a325322adca2cf

05 Affected products

VendorProductVersionsPlatforms
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 2315.01.0.0 to < 15.01.2507.066x64-based Systems
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 1415.02.0.0 to < 15.02.1544.039x64-based Systems
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 1515.02.0.0 to < 15.02.1748.043x64-based Systems
MicrosoftMicrosoft Exchange Server Subscription Edition RTM15.02.0.0 to < 15.02.2562.037x64-based Systems

06 References