immich: One-click account takeover via XSS in login page continue redirect

immich is a high performance self-hosted photo and video management solution. From commit 4ffa26c9 until 4eb1003, a reflected cross-site scripting (XSS) vulnerability on the /auth/login page allows an attacker to fully compromise any authenticated user's account with a single link click. The continue query parameter is read from the URL and passed to SvelteKit's redirect() without any scheme or origin validation, allowing attacker-controlled JavaScript to execute inside Immich's origin. The payload then uses the victim's existing session to mint an all-permission API key on their account, leading to persistent account takeover. This vulnerability is fixed in commit 4eb1003.