Gitea prior to 1.27.0 SSRF via Migration URI Fetch Bypass

Gitea prior to 1.27.0 contains a server-side request forgery vulnerability that allows authenticated attackers to bypass SSRF protections by exploiting HTTP fetch operations in migration and OAuth avatar code paths that use Go's default http.Get without a custom DialContext. Attackers can supply arbitrary URLs through release asset download URLs, pull-request patch URLs, or OAuth avatar endpoints to reach internal services, cloud instance-metadata endpoints, or read local files such as the application configuration containing database credentials and signing secrets, with exfiltrated content persisted as migration release assets for later retrieval.