UI DoS attack

FortiOS web interface is vulnerable to unauthenticated slow HTTP denial-of-service attacks via crafted requests (CVSS 5.0).

Fortinet advisory FG-IR-26-162 details an unbounded resource allocation flaw (CWE-770) in FortiOS, scored CVSSv3 5.0. An unauthenticated attacker can launch a slow HTTP denial-of-service attack against the FortiOS web interface using crafted HTTP requests. The advisory was revised on 2026-08-12 and does not state that exploitation has been observed.

• Unbounded resource allocation (CWE-770) in the FortiOS web interface
• Enables slow HTTP DoS via crafted requests; CVSSv3 5.0
• Unauthenticated, remote attack surface; no exploitation reported