Microsoft Security Advisory CVE-2019-0820: .NET Core Denial of Service Vulnerability #111
Microsoft Security Advisory CVE-2019-0820: .NET Core Denial of Service Vulnerability
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET Core 1.0, 1.1, 2.1 and 2.2. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
A denial of service vulnerability exists when .NET Core improperly process RegEx strings. An attacker who successfully exploited this vulnerability could cause a denial of service against a .NET application.
A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to a .NET Core application.
The update addresses the vulnerability by correcting how .NET Core applications handle RegEx string processing.
Discussion for this issue can be found at https://github.com/dotnet/corefx/issues/37649
There are no mitigating factors for this vulnerability.
Any .NET Core based application that uses the System.Text.RegularExpressions package with a vulnerable version listed below.
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 your version of .NET Core does not support the
Once you have installed the updated runtime or SDK you should 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/. 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.
V1.0 (May 14, 2019): Advisory published.
Last Updated 2019-05-14
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