Inconsistent interpretation of HTTP requests in FortiOS - CVE-2025-55018
Published: February 10, 2026
Vulnerability identifier: #VU122536
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:U/U:Green
CVE-ID: CVE-2025-55018
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Fortinet, Inc
Affected software:
FortiOS
FortiOS
Detailed vulnerability description
The vulnerability allows a remote attacker to perform HTTP request smuggling attacks.
The vulnerability exists due to improper validation of HTTP requests in FortiOS GUI. A remote attacker can smuggle an unlogged HTTP request through the firewall policies via a specially crafted header.
Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.
How to mitigate CVE-2025-55018
Install updates from vendor's website.