CVE-2026-21218

.NET Spoofing Vulnerability

State: Published
Severity: 7.5 High
Published: Feb 10, 2026
Updated: Aug 19, 2026
Reserved: Dec 11, 2025

Description

Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-166 Improper Handling of Missing Special Element

Affected Products

Product	Versions
.NET 10.0Microsoft	10.0.0 to before 10.0.3Affected
.NET 8.0Microsoft	8.0.0 to before 8.0.24Affected
.NET 9.0Microsoft	9.0.0 to before 9.0.13Affected

References

.NET Spoofing Vulnerabilityvendor-advisorypatch

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