Pixelfed's SearchController accepts a URL parameter for remote searching and fetches it server-side via ActivityPubFetchService. The service's URL validation only blocks localhost addresses and requires HTTPS but does not check if the resolved IP is within private or internal ranges. DNS validation is optional and does not filter IP ranges. The fetched response body is returned to authenticated users only if the content type matches ActivityPub types, resulting in a semi-blind SSRF vulnerability accessible to logged-in users.