Basecamp: Open redirect on app.hey.com bypasses HEY desktop's internal-origin allowlist and loads attacker content inside a HEY BrowserWindow

A case-sensitive URL scheme comparison flaw in the proxy image endpoint allowed open redirects on the mail service's web domain. The endpoint failed to recognize uppercase HTTPS scheme variants and redirected users to unproxied URLs instead of properly proxying them. When combined with the deskto...