Authorization bypass through user-controlled key in Serv-U FTP Server - CVE-2026-28317
Published: July 21, 2026 / Updated: July 27, 2026
Vulnerability identifier: #VU139691
CSH Severity: Low
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-28317
CWE-ID: CWE-639
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to escalate privileges.
The vulnerability exists due to insecure direct object reference in Serv-U when handling administrative object references. A remote user can access crafted object references to escalate privileges.
Domain administrator access is required. The impact is lower in Windows deployments.
Affected software
Serv-U FTP Server
How to mitigate CVE-2026-28317
Install security update from vendor's website.
Serv-U FTP Server - update to 2026.3