A critical vulnerability in Admin GUI in Payara Server Full 4.x, 5.x, 6.x, 7.x, 7.2026.x, 6.2025.x, 6.2024.x on All platforms that allows the attacker to leak the admin gfresttoken to an attacker-controlled host that can result in a full unauthenticated takeover of Payara admin domain. A Server-Side Request Forgery (SSRF) vulnerability in the DownloadServlet of the Admin GUI in Payara Server allows a remote attacker to exfiltrate the administrator's REST session token (gfresttoken) to an attacker-controlled host via a crafted request URL. Combined with the absence of CSRF protection on DownloadServlet, an unauthenticated attacker can trick a logged-in administrator into triggering the token leak, then replay the stolen token to gain full administrative access to the Payara domain, leading to arbitrary code execution via WAR deployment. The vulnerability exists in the DownloadServlet and associated ContentSource implementations (LogViewerContentSource, LogFilesContentSource, LBConfigContentSource, ClientStubsContentSource) within the admingui:console-common module.