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Microsoft Security Advisory CVE-2019-1075: ASP.NET Core Spoofing Vulnerability #12007
Microsoft Security Advisory CVE-2019-1075: ASP.NET Core Spoofing Vulnerability
Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core 2.1 and 2.2. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
Microsoft is aware of a spoofing vulnerability that exists in ASP.NET Core that could lead to an open redirect. An attacker who successfully exploited the vulnerability could redirect a targeted user to a malicious website.
To exploit the vulnerability, an attacker could send a link that has a specially crafted URL and convince the user to click the link.
The update addresses the vulnerability by correcting how ASP.NET Core parses URLs.
The original announcement for this issue can be found at aspnet/Announcements#373
Microsoft has not identified any mitigating factors for this vulnerability.
Any ASP.NET Core based application that uses any of following vulnerable packages:
The affected assemblies are part of .NET Core. If you are running a vulnerable version of .NET Core you may be affected.
To fix the issue please install the latest version of .NET Core. If you have multiple versions of .NET Core installed you will need to install multiple runtimes, or SDKs depending on what you have installed.
If you have .NET Core 2.0 or greater installed, you can list the versions you have installed by running the
If you have both 2.1 and 2.2, you need to install updates for both versions.
Once you have installed the updated runtime or SDK, restart your apps for the update to take effect.
If you have pinned your application to a specific version of the runtime, you must update your app, recompile and redeploy it for the update to take effect.
Reporting Security Issues
If you have found a potential security issue in .NET Core, please email details to email@example.com. Reports may qualify for the .NET Core Bug Bounty. Details of the .NET Core Bug Bounty including terms and conditions are at https://aka.ms/corebounty.
You can ask questions about this issue on GitHub in the .NET Core or ASP.NET Core organizations. These are located at https://github.com/dotnet/ and https://github.com/aspnet/, respectively. The Announcements repo for each product (https://github.com/dotnet/Announcements and https://github.com/aspnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the discussion issue.
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
Reported through Datalust
V1.0 (July 9, 2019): Advisory published.
Last Updated 2019-07-09
referenced this issue
Jul 9, 2019
Is there any information whether Kestrel in ASP.NET Core 2.1 hosted behind reverse proxies like NginX or AWS ALB affected (on Linux, no Windows/IIS)?
I'm also a bit unsure how to understand CVE-2019-1075 in general.