request-filtering-agent is an http(s).Agent implementation that blocks requests to Private/Reserved IP addresses. Versions 1.x.x and earlier contain a vulnerability where HTTPS requests to 127.0.0.1 bypass IP address filtering, while HTTP requests are correctly blocked. This allows attackers to potentially access internal HTTPS services running on localhost, bypassing the library's SSRF protection. The vulnerability is particularly dangerous when the application accepts user-controlled URLs and internal services are only protected by network-level restrictions. This vulnerability has been fixed in request-filtering-agent version 2.0.0. Users should upgrade to version 2.0.0 or later.
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.