CVE-2017-0247 in the critical feed json
ASP.NET Core fails to properly validate web requests
published 2017-05-12 9 y ago modified 2026-06-17 4 mo ago also GHSA-6xh7-4v2w-36q6 , EUVD-2018-0527
- cvss
- 7.5
- version 3.0, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 16.9%
- EPSS 16.9% chance of exploitation in 30 days, percentile 97%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nuget Microsoft.AspNetCore.Mvc 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Core 1.0.4, 1.1.3
- nuget System.Net.Http 4.1.2, 4.3.2
- nuget System.Text.Encodings.Web 4.0.1, 4.3.1
- nuget System.Net.Http.WinHttpHandler 4.0.1, 4.5.4
- nuget System.Net.Security 4.0.1, 4.3.1
- nuget System.Net.WebSockets.Client 4.0.1, 4.3.1
- nuget Microsoft.AspNetCore.Mvc.Abstractions 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.ApiExplorer 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Cors 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.DataAnnotations 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Formatters.Json 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Formatters.Xml 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Localization 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Razor.Host 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.Razor 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.TagHelpers 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.ViewFeatures 1.0.4, 1.1.3
- nuget Microsoft.AspNetCore.Mvc.WebApiCompatShim 1.0.4, 1.1.3
Exploit prediction
16.91% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- sidertia.com https://www.sidertia.com/Home/Community/Blog/2017/05/18/ASPNET-Core-Unicode-Non-Char-Encoding-DoS referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.0 | 7.5 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:N/I:P/A:N |
| GitHub | 3.0 | 7.5 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| nuget | Microsoft.AspNetCore.Mvc | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Core | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | System.Net.Http | >=4.1.1, <4.1.2 >=4.3.1, <4.3.2 |
4.1.2 4.3.2 |
| nuget | System.Text.Encodings.Web | >=4.0.0, <4.0.1 >=4.3.0, <4.3.1 |
4.0.1 4.3.1 |
| nuget | System.Net.Http.WinHttpHandler | >=4.0.0, <4.0.1 >=4.3.0, <4.5.4 |
4.0.1 4.5.4 |
| nuget | System.Net.Security | >=4.0.0, <4.0.1 >=4.3.0, <4.3.1 |
4.0.1 4.3.1 |
| nuget | System.Net.WebSockets.Client | >=4.0.0, <4.0.1 >=4.3.0, <4.3.1 |
4.0.1 4.3.1 |
| nuget | Microsoft.AspNetCore.Mvc.Abstractions | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.ApiExplorer | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Cors | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.DataAnnotations | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Formatters.Json | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Formatters.Xml | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Localization | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Razor.Host | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.Razor | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.TagHelpers | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.ViewFeatures | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
| nuget | Microsoft.AspNetCore.Mvc.WebApiCompatShim | >=1.0.0, <1.0.4 >=1.1.0, <1.1.3 |
1.0.4 1.1.3 |
Affected products
- Microsoft Corporation ASP.NET Core
Classification
- Weakness
-
- CWE-20 Improper Input Validation
References
-
technet.microsoft.com
/en-us/library/security/4021279.aspx
web, patch, vendor-advisory
-
sidertia.com
/Home/Community/Blog/2017/05/18/ASPNET-Core-Unicode-Non-Char-Encoding-DoS
web, exploit, third-party-advisory
-
github.com
/aspnet/Announcements/issues/239
web, technical-description, third-party-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2017-0247
advisory
-
github.com
/advisories/GHSA-6xh7-4v2w-36q6
advisory
Sources
- CVE List CVE-2017-0247
- GitHub Advisory GHSA-6xh7-4v2w-36q6
- NVD CVE-2017-0247
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.