Improper handling of exceptional conditions in Serv-U FTP Server - CVE-2026-28318
Published: June 9, 2026 / Updated: July 27, 2026
Vulnerability identifier: #VU134153
CSH Severity: High
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-28318
CWE-ID: CWE-755
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of deflate-encoded post requests in Serv-U service when handling HTTP POST requests with Content-Encoding: deflate. A remote attacker can send a specially crafted HTTP POST request to cause a denial of service.
Note, the vulnerability is being exploited in the wild.
Affected software
Serv-U FTP Server
How to mitigate CVE-2026-28318
Install security update from vendor's website.
Serv-U FTP Server - update to 15.5.4 Hotfix 1