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Asp.net Model View ControllerApplication · Microsoft

CVE-2017-0256

MEDIUM · 5.3 CVSS v3.0 Published 2017-05-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
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
A spoofing vulnerability exists when the ASP.NET Core fails to properly sanitize web requests.

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

A spoofing vulnerability in ASP.NET Core where the framework fails to properly sanitize web requests, potentially allowing attackers to craft malicious requests that bypass validation or impersonate legitimate users.

MitigationUpdate ASP.NET Core to the latest patched version and implement robust input validation and request sanitization in web 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 Model View ControllerApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.abstractionsApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.apiexplorerApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.corsApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.dataannotationsApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.formatters.jsonApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.formatters.xmlApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2
Microsoft.aspnetcore.mvc.localizationApplication
Affected:= 1.0.0= 1.0.1= 1.0.2= 1.0.3= 1.1.0= 1.1.1= 1.1.2

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
Low
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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. Identify installed MVC package versions
    Examine your project's .csproj file or packages.config for references to Microsoft.AspNetCore.Mvc packages (Abstractions, ApiExplorer, Cors, DataAnnotations, Formatters.Json, Formatters.Xml, Localization) or Microsoft.AspNet.Mvc. Run 'dotnet list package' or check NuGet Package Manager for installed versions.
    Affected if Any of these packages are installed with version 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1, or 1.1.2
  2. Verify application uses ASP.NET Core MVC routing
    Inspect your Startup.cs and controller files to confirm the application uses ASP.NET Core MVC for request handling. Look for app.UseMvc() or app.UseMvcWithDefaultRoute() in Startup.cs and controllers inheriting from Controller base class.
    Affected if The application uses ASP.NET Core MVC routing and controllers to process incoming HTTP requests
  3. Check if application accepts external web requests
    Review your application configuration to determine if it listens on network interfaces accessible from external sources. Check Program.cs for URLs bound (e.g., app.UseUrls(), Kestrel configuration) and any firewall or reverse proxy settings.
    Affected if The application accepts HTTP requests from network clients (not localhost-only)

You are affected if your application uses any of the listed ASP.NET Core MVC packages at versions 1.0.0-1.1.2 and processes external web requests.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update ASP.NET Core to the latest patched version and implement robust input validation and request sanitization in web applications.

Fix this in Asp.net Model View Controller Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2017-0256 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