CVE-2026-20180: Cisco ISE Multiple Remote Code Execution Vulnerability

Note

Executive Summary (Sommaire exécutif)

CVE-2026-20180 is a critical-severity (CVSS 9.9) vulnerability in Cisco Identity Services Engine (ISE) that allows an authenticated, remote attacker to execute arbitrary commands on the underlying operating system. Exploitation requires at least Read Only Admin credentials and insufficient validation of user-supplied input via crafted HTTP requests. A successful exploit can lead to root-level access and potential denial of service (DoS).

Technical Analysis

The vulnerability stems from improper input validation within Cisco ISE administrative interfaces. An authenticated user—even one with restricted ‘Read Only Admin’ privileges—can craft specific HTTP requests that bypass input filters, allowing command injection into the underlying OS.

The impact of this vulnerability is significant, as it provides a pathway for an attacker to escalate privileges to root on the affected appliance. Furthermore, in single-node deployments, the attack can trigger a node failure, leading to a denial of service for endpoints relying on ISE for network authentication.

Exploitation Flow

1. Authentication: The attacker authenticates to the Cisco ISE administrative interface using compromised ‘Read Only Admin’ credentials.
2. Request Crafting: The attacker sends a crafted HTTP request designed to exploit the input validation flaw.
3. Execution: The injected command executes on the underlying operating system.
4. Escalation: The attacker leverages the initial command execution to further escalate privileges to root or disrupt service.

Forensic Investigation

When investigating signs of exploitation, prioritize the following actions:

1. HTTP Audit: Review administrative interface access logs for unusual or malformed HTTP requests originating from known admin accounts.
2. Process Monitoring: Analyze process execution logs on the ISE appliance for unexpected commands or processes spawned by ISE service accounts.
3. Privilege Review: Audit all administrative user accounts and roles; disable or restrict accounts with excessive or unnecessary privileges.

Detection

Detecting this exploitation requires monitoring for anomalous behavior targeting the Cisco ISE administrative interfaces. While specific patterns may vary based on deployment, focus on unusual HTTP traffic and unexpected system commands executed by ISE service processes.

Mitigation

Update

Apply the latest security patches provided by Cisco in the official security advisory immediately.

Account Hardening

Audit all administrative accounts. Ensure the principle of least privilege is applied and remove unnecessary access.

Network Segmentation

Restrict access to Cisco ISE administrative interfaces to authorized management networks and trusted IP addresses only.

Sources

• MITRE CVE-2026-20180
• Cisco Security Advisory