Type Confusion in Serv-U FTP Server and Serv-U MFT Server - CVE-2025-40540
Published: February 24, 2026 / Updated: July 27, 2026
Vulnerability identifier: #VU123147
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-40540
CWE-ID: CWE-843
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to a type confusion error. A remote attacker can pass specially crafted data to the application, trigger a type confusion error and execute arbitrary code on the target system.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
Affected software
Serv-U FTP Server
Serv-U MFT Server
Serv-U MFT Server
How to mitigate CVE-2025-40540
Install updates from vendor's website.
Serv-U FTP Server - update to 15.5.4
Serv-U MFT Server - update to 15.5.4
Serv-U MFT Server - update to 15.5.4