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Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability

Type: advisorySource: OSV1 source record

# Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability ## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core IIS out-of-process hosting and request decompression. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. The IIS Middleware for ASP.NET Core did not properly constrain decompression of certain types of request, leading to excess memory consumption and a Denial of Service. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/443 ## CVSS Details - **Version:** 3.1 - **Severity:** Medium - **Score:** 5.9 - **Vector:** `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H` - **Weakness:** CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification)) ## Affected Platforms - **Platforms:** Windows / IIS out-of-process - **Architectures:** All ## Affected Packages The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below ### .NET 11 RC1 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [Microsoft.AspNetCore.Server.IISIntegration](https://www.nuget.org/packages/Microsoft.AspNetCore.Server.IISIntegration) | >= 11.0.0-preview.1, < 11.0.0-rc.1 | 11.0.0-rc.1 ### .NET 10 Package name | Affected version | Patched version ------------ |

Announced Source revision 1
Original source ↗

GHSA-8cp2-47hg-mfgh

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:GHSA-8cp2-47hg-mfgh

Microsoft.AspNetCore.Server.IISIntegration

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
11.0.0-rc.1

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

Microsoft.AspNetCore.Server.IISIntegration

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
8.0.31

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Microsoft.AspNetCore.Server.IISIntegration

Source reference: /affected/2/package/name

Affected versions
Not stated in this record
Fixed versions
9.0.20

Source reference: /affected/2/ranges

Prerequisites
Not stated in this record

Microsoft.AspNetCore.Server.IISIntegration

Source reference: /affected/3/package/name

Affected versions
Not stated in this record
Fixed versions
10.0.12

Source reference: /affected/3/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "11.0.0-preview.1"
          },
          {
            "fixed": "11.0.0-rc.1"
          }
        ]
      }
    ],
    "package": {
      "name": "Microsoft.AspNetCore.Server.IISIntegration",
      "purl": "pkg:nuget/Microsoft.AspNetCore.Server.IISIntegration",
      "ecosystem": "NuGet"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-8cp2-47hg-mfgh/GHSA-8cp2-47hg-mfgh.json"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "8.0.0"
          },
          {
            "fixed": "8.0.31"
          }
        ]
      }
    ],
    "package": {
      "name": "Microsoft.AspNetCore.Server.IISIntegration",
      "purl": "pkg:nuget/Microsoft.AspNetCore.Server.IISIntegration",
      "ecosystem": "NuGet"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-8cp2-47hg-mfgh/GHSA-8cp2-47hg-mfgh.json",
      "last_known_affected_version_range": "<= 8.0.30"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "9.0.0"
          },
          {
            "fixed": "9.0.20"
          }
        ]
      }
    ],
    "package": {
      "name": "Microsoft.AspNetCore.Server.IISIntegration",
      "purl": "pkg:nuget/Microsoft.AspNetCore.Server.IISIntegration",
      "ecosystem": "NuGet"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-8cp2-47hg-mfgh/GHSA-8cp2-47hg-mfgh.json",
      "last_known_affected_version_range": "<= 9.0.19"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "10.0.0"
          },
          {
            "fixed": "10.0.12"
          }
        ]
      }
    ],
    "package": {
      "name": "Microsoft.AspNetCore.Server.IISIntegration",
      "purl": "pkg:nuget/Microsoft.AspNetCore.Server.IISIntegration",
      "ecosystem": "NuGet"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-8cp2-47hg-mfgh/GHSA-8cp2-47hg-mfgh.json",
      "last_known_affected_version_range": "<= 10.0.11"
    }
  }
]
Related CVEs
CVE-2026-69304

Source reference: /aliases

Publisher severity

No explicit severity was provided.

Linked CVE context

These ratings describe the referenced vulnerabilities and products. They are not a severity rating for every application using this dependency.

CVE-2026-69304 · Medium

.NET 10.0, .NET 8.0, .NET 9.0, ASP.NET Core 10.0, ASP.NET Core 11.0, ASP.NET Core 8.0, ASP.NET Core 9.0, Microsoft Visual Studio 2022 version 17.14, Microsoft Visual Studio 2026 version 18.9

CVE-2026-69304 · Medium

aspnet-core

CVE-2026-69304 · Medium

dotnet

CVE-2026-69304 · Medium

dotnet-sdk

Event
#60882 · Revision 1
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