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CVE-2026-21218

.NET Spoofing Vulnerability

Published: Feb 10, 2026Updated: Feb 12, 2026 Sources: CVE List NVD GHSA BDUCWE-166
NVD MITRE
7.5CVSSHIGH
EPSS Score
1.0%
Top 41.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

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

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-166

Affected Products

.netmicrosoft
Library
OSS Libraries / generic-library
.NET 10.0Microsoft
On-prem
Operating Systems / windows
.NET 8.0Microsoft
LibraryLibrary
OSS Libraries / generic-library
.NET 9.0Microsoft
MixedLibrary
OSS Libraries / generic-library
System.Security.Cryptography.CoseNuGetOSS Libraries
microsoftcommercialUSOperating Systems
nugetpackage-ecosystemOSS Libraries
and 2 more affected products View all →

Exploitability

Official Patch Available

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21218
msrc.microsoft.com
https://github.com/dotnet/runtime/security/advisories/GHSA-qvhc-9v3j-5rfw
github.com
https://nvd.nist.gov/vuln/detail/CVE-2026-21218
nvd.nist.gov
and 3 more references View all →

Timeline

Published
Feb 10, 2026
Last Updated
Feb 12, 2026

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