Spoofing Vulnerability in .NET Framework by Microsoft
CVE-2026-21218

7.5HIGH

Key Information:

Vendor

Microsoft
Status
.net 10.0
.net 8.0
.net 9.0
Vendor
CVE Published:
10 February 2026

What is CVE-2026-21218?

An improper handling of missing special elements in the .NET Framework could allow an unauthorized attacker to spoof identity or data over a network, posing significant risks to application integrity and security. Organizations utilizing affected versions are advised to review their security posture and implement the necessary updates to mitigate potential exploitation.

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Deploy the Patch

Affected Version(s)

.NET 10.0 10.0.0 < 10.0.3

.NET 8.0 8.0.0 < 8.0.24

.NET 9.0 9.0.0 < 9.0.13

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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