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Miggo AIRoot Cause AnalysisThe vulnerability, CVE-2026-69304, describes a Denial of Service (DoS) in ASP.NET Core due to 'Improper Handling of Highly Compressed Data (Data Amplification)' (CWE-409). Specifically, the 'IIS Middleware for ASP.NET Core did not properly constrain decompression of certain types of request, leading to excess memory consumption.'
My analysis focused on identifying the component responsible for this lack of constraint. The affected package is Microsoft.AspNetCore.Server.IISIntegration, and within its source code, IISMiddleware.cs contains the IISMiddleware class, which is the core of this integration. The Invoke method within this class is the primary entry point for processing HTTP requests handled by this middleware.
Although the explicit decompression logic was not found directly within the IISMiddleware.Invoke method (suggesting it might occur at a lower level, possibly within the native ASP.NET Core Module), the vulnerability description clearly states that the middleware failed to 'constrain' this decompression. Therefore, the Invoke method, by allowing the unconstrained processing of such requests, is the vulnerable function in the C# codebase. The fix would involve adding checks or configurations within this method or its call chain to limit the decompressed size or reject overly compressed requests.
Due to the absence of direct commit URLs or patch files in the provided advisory and related discussions, I could not perform a direct diff analysis. However, the detailed description of the vulnerability and the identified affected component strongly indicate that the IISMiddleware.Invoke method is the function that would be active during the exploitation of this vulnerability, as it's the entry point for the unconstrained request processing.
Microsoft.AspNetCore.Server.IISIntegration.IISMiddleware.Invokesrc/Servers/IIS/IISIntegration/src/IISMiddleware.cs
| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| Microsoft.AspNetCore.Server.IISIntegration | nuget | >= 11.0.0-preview.1, < 11.0.0-rc.1 | 11.0.0-rc.1 |
| Microsoft.AspNetCore.Server.IISIntegration | nuget | >= 8.0.0, <= 8.0.30 | 8.0.31 |
| Microsoft.AspNetCore.Server.IISIntegration | nuget | >= 9.0.0, <= 9.0.19 | 9.0.20 |
| Microsoft.AspNetCore.Server.IISIntegration | nuget | >= 10.0.0, <= 10.0.11 | 10.0.12 |