.NET
CVE-2026-21218 — .NET Spoofing Vulnerability
Executive Summary
Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.
Overview
7.5
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Exploitation Unlikely
MS Exploit Likelihood
CVSS Vector
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
Temporal Score: 6.5
EPSS Score
0.01015
probability of exploitation in the next 30 days
0.58742 percentile - updated 2026-06-20
View on FIRST.org
Affected Products
9 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| .NET 10.0 installed on Linux | 5077862 (Security Update) |
Important | Spoofing | Maybe |
| .NET 10.0 installed on Mac OS | 5077862 (Security Update) |
Important | Spoofing | Maybe |
| .NET 10.0 installed on Windows | 5077862 (Security Update) |
Important | Spoofing | Maybe |
| .NET 8.0 installed on Linux | 5077863 (Security Update) |
Important | Spoofing | Maybe |
| .NET 8.0 installed on Mac OS | 5077863 (Security Update) |
Important | Spoofing | Maybe |
| .NET 8.0 installed on Windows | 5077863 (Security Update) |
Important | Spoofing | Maybe |
| .NET 9.0 installed on Linux | 5077864 (Security Update) |
Important | Spoofing | Maybe |
| .NET 9.0 installed on Mac OS | 5077864 (Security Update) |
Important | Spoofing | Maybe |
| .NET 9.0 installed on Windows | 5077864 (Security Update) |
Important | Spoofing | Maybe |
Patches
3 patches
| Article | Type | Restart |
|---|---|---|
5077862 |
Security Update | Maybe |
5077863 |
Security Update | Maybe |
5077864 |
Security Update | Maybe |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
vcsjones with GitHub
References
On This Page