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Privacy Statement Third-Party Cookies Accept Reject Manage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-40372 ASP.NET Core Elevation of Privilege Vulnerability New On this page  CVE-2026-40372  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: Apr 21, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-40372  Impact Elevation of Privilege Max Severity Important Weakness CWE-347: Improper Verification of Cryptographic Signature CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C Metrics CVSS:3.1 9.1 / 7.9  Base score metrics: 9.1 / Temporal score metrics: 7.9  Expand all  Collapse all Metric Value   Base score metrics(8) Attack Vector Network Attack Complexity Low Privileges Required None User Interaction None Scope Unchanged Confidentiality High Integrity High Availability None   Temporal score metrics(3) Exploit Code Maturity Unproven Remediation Level Official Fix Report Confidence Confirmed Please see Common Vulnerability Scoring System for more information on the definition of these metrics. Executive Summary Improper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network. Exploitability The following table provides an exploitability assessment for this vulnerability at the time of original publication. Publicly disclosed No Exploited No Exploitability assessment Exploitation Less Likely FAQ How do I know if I'm affected? You are affected if all three of the following are true: Your application uses Microsoft.AspNetCore.DataProtection 10.0.6 from NuGet (directly, or through a package that depends on it such as Microsoft.AspNetCore.DataProtection.StackExchangeRedis). The NuGet copy of the library was actually loaded at runtime — not the shared framework copy. This typically means you deploy self-contained, or your installed shared framework is older than the NuGet package version. Your application runs on Linux, macOS, or another non-Windows OS. How do I determine if the vulnerable binary was loaded? Check application logs. The clearest symptom is users being logged out and repeated "The payload was invalid" errors in your logs after upgrading to 10.0.6. Check your project file. Look for a PackageReference to Microsoft.AspNetCore.DataProtection version 10.0.6 in your .csproj file (or in a package that depends on it). You can also run dotnet list package to see resolved package versions. Inspect the binary on disk. See [https://file+.vscode-resource.vscode-cdn.net/c%3A/Users/shalter/Downloads/advisory-upd-1.md#technical-details]Technical details for how to distinguish the affected NuGet binary from the correct shared framework binary by file size. Additional information Shared framework deployments are not affected. If your application runs framework-dependent and the installed ASP.NET Core shared framework version is ≥ your Microsoft.AspNetCore.DataProtection PackageReference version, the correct shared framework binary is loaded and the NuGet binary is never used. Windows deployments are not affected. On Windows, DataProtection uses CNG-based encryptors by default, which do not contain this bug. 8.0.x and 9.0.x packages are not affected. The defective code path was introduced during 10.0 development and was never backported. Windows with managed algorithms: If you run on Windows but explicitly opted into managed algorithms via UseCustomCryptographicAlgorithms, you are also affected. Older target frameworks: A smaller population running net462 / netstandard2.0 with Microsoft.AspNetCore.DataProtection 10.0.0–10.0.6 is affected on all operating systems. See [https://file+.vscode-resource.vscode-cdn.net/c%3A/Users/shalter/Downloads/advisory-upd-1.md#technical-details]Technical details for specifics. https://github.com/dotnet/announcements/issues/395 What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges. According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of confidentiality (C:H), and integrity (I:H), but could lead to no loss of availability (A:N). What does that mean for this vulnerability? Exploiting this vulnerability could allow an attacker to disclose files and modify data, but the attacker cannot impact the availability of the system. Acknowledgements Anonymous Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information. Security Updates To determine the support lifecycle for your software, see the Microsoft Support Lifecycle. Release date Descending  Edit columns  Download  Filters  Product Family  Max Severity  Impact  Platform   Clear Release date  Product Platform Impact Max Severity Article Download Build Number Assigning CNA Customer Action Required Title: Release date, Content: Apr 21, 2026 ASP.NET Core 10.0 - Elevation of Privilege Important Title: Knowledge Base Articles for ASP.NET Core 10.0, Content:, 1 link 5091596  Title: Download Security Update for ASP.NET Core 10.0, Content:, 1 link Security Update  Title: Build numbers, Content: 10.0.7 Title: Assigning CNA, Content: Microsoft Title: Customer action required, Content: Required All results loaded Loaded all 1 rows Disclaimer The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions version revisionDate description 1.0 Apr 21, 2026 Information published.  How satisfied are you with the MSRC Security Update Guide? Rating  Broken  Bad  Below average  Average  Great!  Your Privacy Choices Consumer Health Privacy