What’s Vulnerable › Vulnerabilities

CVE-2017-0247

• Severity: high (CVSS 7.5 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 16.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2017-05-12 · updated 2026-06-17
• Weakness: CWE-20

Description

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 products

• Microsoft Asp.Net Model View Controller: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Abstractions: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Apiexplorer: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Cors: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Dataannotations: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Formatters.Json: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Formatters.Xml: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Localization: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Razor: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Razor.Host: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Taghelpers: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Viewfeatures: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft.Aspnetcore.Mvc.Webapicompatshim: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1 (+1)
• Microsoft System.Net.Http: 4.1.1, 4.3.1
• Microsoft System.Net.Http.Winhttphandler: 4.0.1, 4.3.0
• Microsoft System.Net.Security: 4.0.0, 4.3.0
• Microsoft System.Net.Websockets.Client: 4.0.0, 4.3.0
• Microsoft System.Text.Encodings.Web: 4.0.0, 4.3.0

References

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

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