mod_http_oauth2: Reject loopback URIs as client_uri
This really should be a proper website with info, https://localhost is
not good enough. Ideally we'd validate that it's got proper DNS and is
actually reachable, but triggering HTTP or even DNS lookups seems like
it would carry abuse potential that would best to avoid.
--- a/mod_http_oauth2/mod_http_oauth2.lua Tue May 02 16:14:22 2023 +0200
+++ b/mod_http_oauth2/mod_http_oauth2.lua Tue May 02 16:20:55 2023 +0200
@@ -754,7 +754,7 @@
end
local client_uri = url.parse(client_metadata.client_uri);
- if not client_uri or client_uri.scheme ~= "https" then
+ if not client_uri or client_uri.scheme ~= "https" or loopbacks:contains(client_uri.host) then
return nil, oauth_error("invalid_request", "Missing, invalid or insecure client_uri");
end