GeoServer is an open source server that allows users to share and edit geospatial data. The Coverage rest api /workspaces/{workspaceName}/coveragestores/{storeName}/{method}.{format} allows attackers to upload files with a specified url (with {method} equals url) with no restrict. This vulnerability is fixed in 2.26.0.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.