CVE-2026-70181: Microsoft Security Advisory CVE-2026-70181 - ASP.NET Core Denial of Service Vulnerability

October 13, 2026 (updated October 19, 2026)

Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.WebUtilities. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

FileBufferingReadStream eagerly rents buffers during multipart processing, allowing memory exhaustion and denial of service.

References

github.com/advisories/GHSA-w5qq-qrpp-rf4c
github.com/dotnet/announcements/issues/459
github.com/dotnet/aspnetcore/discussions/69795
github.com/dotnet/aspnetcore/security/advisories/GHSA-w5qq-qrpp-rf4c
msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70181
nvd.nist.gov/vuln/detail/CVE-2026-70181

Code Behaviors & Features

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