Vulnerability in Microsoft.AspNetCore.Server.IISIntegration (CVE-2026-69304)
Summary
Vulnerability in Microsoft.AspNetCore.Server.IISIntegration (CVE-2026-69304). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 10.0.12 or later.
Original description
The description as published by the source.
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 | >= 11.0.0-preview.1, < 11.0.0-rc.1 | 11.0.0-rc.1 |
.NET 10
Package name | Affected version | Patched version
---…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-69304 has been found in Microsoft.AspNetCore.Server.IISIntegration.
Risk of unauthorized operations or information disclosure. CVSS score: 5.9/10.
What to do: upgrade Microsoft.AspNetCore.Server.IISIntegration to 10.0.12 or later.
If unsure, ask your IT team or search "Microsoft.AspNetCore.Server.IISIntegration CVE-2026-69304" on the vendor's site.
CVE-2026-69304 (Microsoft.AspNetCore.Server.IISIntegration) — CWE-409 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 10.0.12 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-409) exists in Microsoft.AspNetCore.Server.IISIntegration.
Check the vendor advisory for the affected versions of Microsoft.AspNetCore.Server.IISIntegration.
Severity: Medium (CVSS 5.9/10). Risk of unauthorized operations or information disclosure.
Update to 10.0.12.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Microsoft.AspNetCore.Server.IISIntegration' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Microsoft.AspNetCore.Server.IISIntegration' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Microsoft.AspNetCore.Server.IISIntegrationを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Microsoft.AspNetCore.Server.IISIntegration to 10.0.12ステージング環境で 10.0.12 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web msrc.microsoft.com
- web github.com
- web nvd.nist.gov
- web github.com