Description

A critical vulnerability has been disclosed in Wing FTP Server, tracked as CVE-2025-47812, which allows unauthenticated remote code execution (RCE), potentially resulting in full server takeover. This flaw, present in versions up to and including 7.4.3, stems from improper handling of NULL bytes in the /loginok.html endpoint’s username parameter. An attacker can exploit this by injecting malicious Lua code into session files through a crafted HTTP POST request, gaining system-level access. Given that Wing FTP often runs with elevated privileges—root on Linux and NT AUTHORITY/SYSTEM on Windows—the exploit can fully compromise affected systems. The issue is particularly dangerous when anonymous user access is enabled, as it eliminates the need for authentication. The vulnerability was discovered by researcher Julien Ahrens and carries a CVSSv4 score of 10.0, reflecting its ease of exploitation and severity. Attackers can execute arbitrary commands remotely by submitting a payload with a malicious username value. Since Wing FTP is widely used across various platforms and industries, the impact of this flaw could be far-reaching, potentially affecting thousands of systems globally. The public disclosure and availability of a proof-of-concept (PoC) increase the risk of widespread exploitation. Organizations using Wing FTP Server are strongly urged to upgrade to version 7.4.4, which includes the necessary patch. Additionally, administrators should audit server logs for suspicious activity, disable anonymous access if not required, and apply strict access controls. Regular vulnerability assessments and patch management processes are essential to mitigate such threats and prevent future security incidents.