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This security advisory details a critical vulnerability identified within Microsoft.AspNetCore.WebUtilities, specifically affecting how the FileBufferingReadStream handles request data processing. During multipart processing operations, the underlying component eagerly rents buffers from memory pools without enforcing adequate throttling or upper allocation bounds. An unauthenticated remote attacker can exploit this design flaw by streaming specially crafted payloads or large volumes of multipart data to the target application endpoint. Because the framework continuously allocates and retains memory buffers faster than the garbage collector or application logic can release them, it rapidly drives up resource consumption. This unrestricted memory allocation pattern exhausts available system memory (RAM), culminating in severe application instability and a complete denial of service (DoS) condition for legitimate users. To remediate this risk, developers must immediately update their .NET runtime packages, SDK dependencies, and any self-contained application deployments to the patched software versions.
DailyCVE Form:
Platform: Microsoft .NET
Version: 8.0, 9.0, 10.0
Vulnerability :Denial of Service
Severity: High
date: 10/13/2026
Prediction: October 2026
What Undercode Say:
dotnet --info dotnet add package Microsoft.AspNetCore.App.Runtime --version 9.0.21
Exploit: (Educational Purposes!)
An attacker sends a high volume of malformed multipart HTTP POST requests with large boundary sizes to an exposed ASP.NET Core web endpoint. The vulnerable `FileBufferingReadStream` eagerly allocates memory buffers for each stream segment without imposing resource caps, causing rapid memory exhaustion and application crashes.
Protection: from this CVE
Update .NET runtime and SDK packages to versions 8.0.32, 9.0.21, or 10.0.13 respectively, restart all running web applications, and recompile any self-contained deployments.
Impact:
Unauthenticated remote attackers can trigger sustained memory exhaustion, leading to application crashes and complete denial of service for users.
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Sources:
Reported By: github.com
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