Describe CVE-2021-41238.
What is CVE-2021-41238?
Hangfire is an open source system to perform background job processing in a .NET or .NET Core applications. No Windows Service or separate process required. Dashboard UI in Hangfire.Core uses authorization filters to protect it from showing sensitive data to unauthorized users. By default when no custom authorization filters specified, `LocalRequestsOnlyAuthorizationFilter` filter is being used to allow only local requests and prohibit all the remote requests to provide sensible, protected by default settings. However due to the recent changes, in version 1.7.25 no authorization filters are used by default, allowing remote requests to succeed. If you are using `UseHangfireDashboard` method with default `DashboardOptions.Authorization` property value, then your installation is impacted. If any other authorization filter is specified in the `DashboardOptions.Authorization` property, the you are not impacted. Patched versions (1.7.26) are available both on Nuget.org and as a tagged release on the github repo. Default authorization rules now prohibit remote requests by default again by including the `LocalRequestsOnlyAuthorizationFilter` filter to the default settings. Please upgrade to the newest version in order to mitigate the issue. For users who are unable to upgrade it is possible to mitigate the issue by using the `LocalRequestsOnlyAuthorizationFilter` explicitly when configuring the Dashboard UI..