FreeScout: Server-side request forgery via incomplete outbound host validation and unguarded download sinks

Overview

FreeScout is a self-hosted help desk and shared mailbox. Prior to 1.8.230, multiple outbound paths in Helper::downloadRemoteFile(), Helper::checkPort(), Helper::sanitizeRemoteUrl(), MailboxesController.php, and ModulesController.php do not consistently enforce a sink-level restricted-host policy. An authenticated administrator, or another authenticated user permitted to change mailbox connection settings or trigger module update or installation paths, can supply attacker-controlled URLs or hosts. The independent download and port-test sinks can reach encoded or otherwise uncovered loopback and internal addresses. The redirect-validation bypass additionally requires a configured whitelist that permits the original and final hosts while a restricted internal host appears only as an intermediate redirect hop. No unauthenticated SSRF path is established. The server can consequently contact loopback and internal services, provide a blind internal port oracle, and retrieve internal HTTP responses into application-controlled download sinks. This issue is fixed in version 1.8.230.

Affected

• freescout < 1.8.230

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.