Fediverse Embeds < 1.5.8 - Unauthenticated SSRF via Site Info Endpoint

The Fediverse Embeds WordPress plugin before 1.5.8 does not validate the destination of the server-side request performed by an unauthenticated site-info endpoint before fetching it, allowing anonymous users (the gating nonce is exposed on public pages carrying an embed) to make the site request internal and private-network URLs and read back the parsed page metadata. This is a Server-Side Request Forgery.