The Easy Social Icons WordPress plugin before 4.0.3 does not sanitise SVG files, which it adds to the list of file types that may be uploaded site-wide, allowing users with the Author role and above to upload a malicious SVG containing XSS payloads. Where another installed Easy Social Icons WordPress plugin before 4.0.3 exposes an upload route to unauthenticated visitors, the same issue can be triggered without an account.