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Asp.net CoreApplication · Microsoft

CVE-2026-45591

HIGH · 7.5 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 8.0.28 / 9.0.17 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Uncontrolled resource consumption in ASP.NET Core allows an unauthorized attacker to deny service over a network.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 2mo ago

Surfaced from public web coverage — external links open in a new tab.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is an uncontrolled resource consumption vulnerability in ASP.NET Core that allows an unauthorized attacker to cause denial of service over a network by exhausting server resources (likely memory, CPU, or concurrent connections).

MitigationApply the Microsoft security update for ASP.NET Core when available, and implement or verify request size limits, connection timeouts, and request throttling configurations in affected applications.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Asp.net CoreApplication
Affected:>= 8.0.0, < 8.0.28>= 9.0.0, < 9.0.17>= 10.0.0, < 10.0.9
Visual Studio 2026Application
Affected:>= 18.6.0, < 18.6.3
.netApplication
Affected:>= 8.0.0, < 8.0.28>= 9.0.0, < 9.0.17>= 10.0.0, < 10.0.9

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check .NET runtime version
    Run 'dotnet --version' in a command prompt or terminal to determine the installed .NET runtime version.
    Affected if The version falls within 8.0.0 to 8.0.27, 9.0.0 to 9.0.16, or 10.0.0 to 10.0.8.
  2. Check ASP.NET Core runtime version
    Run 'dotnet --list-runtimes' and look for entries starting with 'Microsoft.AspNetCore.App' to identify the installed ASP.NET Core runtime version.
    Affected if The ASP.NET Core runtime version is 8.0.x before 8.0.28, 9.0.x before 9.0.17, or 10.0.x before 10.0.9.
  3. Verify if application uses ASP.NET Core web hosting
    Inspect the project file (.csproj) for a 'Microsoft.AspNetCore.App' reference, or check if the application runs a web host (Kestrel, IIS, or HTTP.sys).
    Affected if The application hosts an ASP.NET Core web server and the runtime version is in the affected range.
  4. Check Visual Studio 2026 version (if applicable)
    Open Visual Studio 2026, go to Help > About Microsoft Visual Studio, and note the version number.
    Affected if Visual Studio version is 18.6.0 through 18.6.2.

If the ASP.NET Core or .NET runtime version is 8.0.0-8.0.27, 9.0.0-9.0.16, or 10.0.0-10.0.8, or Visual Studio 2026 is 18.6.0-18.6.2, the environment is affected by this DoS vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.0.28 / 9.0.17 / 10.0.9 or later
Fixed in 8.0.289.0.1710.0.9
Interim mitigation

Apply the Microsoft security update for ASP.NET Core when available, and implement or verify request size limits, connection timeouts, and request throttling configurations in affected applications.

Recommended fix High confidence

Upgrade to .NET 8.0.28 / 9.0.17 / 10.0.9 (or later), or Visual Studio 2026 18.6.3

  1. Identify your current .NET/ASP.NET Core version by checking your project file (e.g., <TargetFramework>net8.0</TargetFramework>) or running 'dotnet --version'
  2. For .NET 8.0.x applications: Upgrade to .NET 8.0.28 or later by updating the TargetFramework to 'net8.0' and restoring packages
  3. For .NET 9.0.x applications: Upgrade to .NET 9.0.17 or later by updating the TargetFramework to 'net9.0' and restoring packages
  4. For .NET 10.0.x applications: Upgrade to .NET 10.0.9 or later by updating the TargetFramework to 'net10.0' and restoring packages
  5. For Visual Studio 2026: Upgrade to version 18.6.3 or later via the Visual Studio Installer
  6. Run your application tests after upgrade to verify compatibility
  7. Ensure the upgraded runtime is deployed to all production environments
Caveat Major version upgrades (e.g., 8.x to 9.x to 10.x) may have breaking API changes; review release notes and test thoroughly

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Asp.net Core Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,448.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45591 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data