Feb 2026: .NET Spoofing Vulnerability
CVE-2026-21218 Published on February 10, 2026
.NET Spoofing Vulnerability
Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.
Weakness Type
Improper Handling of Missing Special Element
The software receives input from an upstream component, but it does not handle or incorrectly handles when an expected special element is missing.
Products Associated with CVE-2026-21218
Want to know whenever a new CVE is published for Microsoft Net? stack.watch will email you.
Affected Versions
Microsoft .NET 10.0:- Version 10.0.0 and below 10.0.3 is affected.
- Version 8.0.0 and below 8.0.24 is affected.
- Version 9.0.0 and below 9.0.13 is affected.
Vulnerable Packages
The following package name and versions may be associated with CVE-2026-21218
| Package Manager | Vulnerable Package | Versions | Fixed In |
|---|---|---|---|
| nuget | System.Security.Cryptography.Cose | >= 8.0.0, <= 8.0.1 | 8.0.2 |
| nuget | System.Security.Cryptography.Cose | >= 9.0.0, <= 9.0.12 | 9.0.13 |
| nuget | System.Security.Cryptography.Cose | >= 10.0.0, <= 10.0.2 | 10.0.3 |
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.