Unauthenticated network spoofing through System.Net.Mail
Published Apr 14, 2026 · Updated Apr 14, 2026
Improper neutralization in System.Net.Mail in .NET 8, 9, 10 and Visual Studio 2022 allows remote attackers to spoof data over a network. Microsoft has not disclosed which special elements are accepted or the exact System.Net.Mail operation that mishandles the crafted data. Exposure requires an application to use an affected runtime package and process attacker-controlled mail data; the published assessment limits impact to confidentiality.
Summary
What happened
Improper neutralization in System.Net.Mail in .NET 8, 9, 10 and Visual Studio 2022 allows remote attackers to spoof data over a network. Microsoft has not disclosed which special elements are accepted or the exact System.Net.Mail operation that mishandles the crafted data. Exposure requires an application to use an affected runtime package and process attacker-controlled mail data; the published assessment limits impact to confidentiality.
The record
- CVE
- CVE-2026-32178
- Published
- Apr 14, 2026
- Updated
- Apr 14, 2026
- Vendor
- Microsoft
- Product
- .NET 9.0
- Classifications
- CWE-138
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 14, 2026CVE publishedPublication date reported by the CVE source.
- Apr 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=9.0.0 <9.0.15
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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