Summary
Impact: Information Disclosure. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
What type of information could be disclosed by this vulnerability?
Exploiting this vulnerability could allow the disclosure of credentials.
According to the CVSS metric, the attack complexity is high (AC:H). What does this mean for this vulnerability?
An attacker would need specific conditions to be in place (i.e. particular protocol settings, or configurations, etc.) before an attack could succeed, which reduces the likelihood of widespread or opportunistic exploitation.
Security updates
11.0.0-rc.2 — https://github.com/dotnet/announcements/issues/448
10.0.13 — https://support.microsoft.com/help/5130036
8.0.32 — https://support.microsoft.com/help/5130034
9.0.21 — https://support.microsoft.com/help/5130035
17.14.42 — https://learn.microsoft.com/en-us/visualstudio/releases/2022/release-notes
18.10.4 — https://learn.microsoft.com/en-us/visualstudio/releases/2026/release-notes
Vulnerabilities 1
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Medium 5.9
.NET Information Disclosure Vulnerability
Insertion of sensitive information into sent data in .NET allows an unauthorized attacker to disclose information over a network.
Revision history
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#2
Updated the Security Updates table to add KB article links for .NET 11.0. This is an informational change only; the fixed builds are unchanged.
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#1
Information published.
References
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CVE-2026-66822 .NET Information Disclosure Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66822
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss