.netApplication · Microsoft

CVE-2026-42899

HIGH · 7.5 CVSS v3.1 Published 2026-05-12

Fix available

A fix is available. Upgrade to 8.0.27 / 9.0.16 or later.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

Loop with unreachable exit condition ('infinite loop') in ASP.NET Core allows an unauthorized attacker to deny service over a network.

Technical summary

dbcve analysis · moderate confidence

An infinite loop vulnerability exists in ASP.NET Core where a loop contains an unreachable exit condition, allowing an unauthenticated remote attacker to trigger a denial of service by causing the affected component to loop indefinitely and consume resources.

MitigationApply the official Microsoft security update for ASP.NET Core when released; meanwhile, implement network-level rate limiting and request monitoring to detect and mitigate potential exploitation attempts.

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

Affected products & versions

NVD · CPE data

.netApplication

Affected:>= 8.0.0, < 8.0.27>= 9.0.0, < 9.0.16>= 10.0.0, < 10.0.8

CVSS breakdown

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?

dbcve checks

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

Identify installed .NET SDK version

Run command: dotnet --version

Affected if The version displayed is 8.0.0 through 8.0.26, 9.0.0 through 9.0.15, or 10.0.0 through 10.0.7
Identify installed ASP.NET Core runtime versions

Run command: dotnet --list-runtimes | grep -i aspnetcore

Affected if Any displayed Microsoft.AspNetCore.App runtime version falls within 8.0.0-8.0.26, 9.0.0-9.0.15, or 10.0.0-10.0.7
Check for ASP.NET Core apps running on the system

Review running processes or services that use ASP.NET Core; check IIS sites if applicable using: appcmd list site

Affected if Any ASP.NET Core application is hosted and the underlying runtime version is in the affected ranges listed above

A user is affected if any .NET SDK or ASP.NET Core runtime installed on the system falls within versions 8.0.0-8.0.26, 9.0.0-9.0.15, or 10.0.0-10.0.7.

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

Remediation

dbcve · scoped

Upgrade available Upgrade to 8.0.27 / 9.0.16 / 10.0.8 or later

Fixed in 8.0.279.0.1610.0.8

Interim mitigation

Apply the official Microsoft security update for ASP.NET Core when released; meanwhile, implement network-level rate limiting and request monitoring to detect and mitigate potential exploitation attempts.

Recommended fix High confidence

Upgrade to .NET 8.0.27+ / 9.0.16+ / 10.0.8+ depending on your major version branch

Identify the current .NET version by running 'dotnet --version' in your application environment
Review your project files (.csproj) to confirm the target framework version (e.g., <TargetFramework>net8.0</TargetFramework>)
Update the .NET SDK to the fixed version: for .NET 8, upgrade to 8.0.27 or later; for .NET 9, upgrade to 9.0.16 or later; for .NET 10, upgrade to 10.0.8 or later
Update the runtime version in your deployment environment to match the SDK version
Rebuild and redeploy your ASP.NET Core applications
Verify the application starts and responds correctly after the update

Caveat Review .NET release notes for any breaking changes between your current version and the target patched version; minor version upgrades typically have minimal breaking changes but test thoroughly

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

Fix this in .net Scoped from the published advisory

Consultation4.0 h
Implementation6.0 h
Testing8.0 h
Review / QA4.0 h

22.0 hours of engineering $3,800

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,080.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

Check whether your project pulls in CVE-2026-42899 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42899 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-42899?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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

At a glance

A fix existsUpgrade to 8.0.27 / 9.0.16 or later

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 2.4%

Affects: .net

Remediation

A high-priority fix

Fix this in .net 22 hrs · Moderate

Typical engagement from $3,800

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-42899 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

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

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References