ASP.NET Core fails to properly validate web requests
A denial of service vulnerability exists when the ASP.NET Core fails to properly validate web requests. NOTE: Microsoft has not commented on third-party claims that the issue is that the TextEncoder.EncodeCore function in the System.Text.Encodings.Web package in ASP.NET Core Mvc before 1.0.4 and 1.1.x before 1.1.3 allows remote attackers to cause a denial of service by leveraging failure to properly calculate the length of 4-byte characters in the Unicode Non-Character range.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | Microsoft.AspNetCore.Mvc | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Abstractions | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.ApiExplorer | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Core | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Cors | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.DataAnnotations | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Formatters.Json | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Formatters.Xml | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Localization | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Razor | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.Razor.Host | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.TagHelpers | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.ViewFeatures | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | Microsoft.AspNetCore.Mvc.WebApiCompatShim | >= 1.0.0, < 1.0.4, >= 1.1.0, < 1.1.3 | 1.0.4, 1.1.3 |
| .NET (NuGet) | System.Net.Http | >= 4.1.1, < 4.1.2, >= 4.3.1, < 4.3.2 | 4.1.2, 4.3.2 |
| .NET (NuGet) | System.Net.Http.WinHttpHandler | >= 4.0.0, < 4.0.1, >= 4.3.0, < 4.5.4 | 4.0.1, 4.5.4 |
| .NET (NuGet) | System.Net.Security | >= 4.0.0, < 4.0.1, >= 4.3.0, < 4.3.1 | 4.0.1, 4.3.1 |
| .NET (NuGet) | System.Net.WebSockets.Client | >= 4.0.0, < 4.0.1, >= 4.3.0, < 4.3.1 | 4.0.1, 4.3.1 |
| .NET (NuGet) | System.Text.Encodings.Web | >= 4.0.0, < 4.0.1, >= 4.3.0, < 4.3.1 | 4.0.1, 4.3.1 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2017-0247
- https://github.com/aspnet/Announcements/issues/239
- https://github.com/advisories/GHSA-6xh7-4v2w-36q6
- https://technet.microsoft.com/en-us/library/security/4021279.aspx
- https://www.sidertia.com/Home/Community/Blog/2017/05/18/ASPNET-Core-Unicode-Non-Char-Encoding-DoS
- CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- Weakness (CWE)
CWE-20- Platform
- .NET (NuGet)
- Package
Microsoft.AspNetCore.Mvc, Microsoft.AspNetCore.Mvc.Abstractions, Microsoft.AspNetCore.Mvc.ApiExplorer- Disclosed
- 16.10.2018
- Updated
- 11.10.2026 11:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-6xh7-4v2w-36q6 - CC BY 4.0
Vulnerability history: Microsoft.AspNetCore.Mvc.Formatters.Xml
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 10.2018 10.2018
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 2
Disclosures per year
- 2018: 4
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
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ASP.NET Core fails to properly validate web requests this entry
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