External risk intelligence

Cisco ISE and PIC can be compromised to take control of systems and disrupt network access

CVE advisorySeverity: CRITICAL (CVSS 9.9)

CVE-2026-20147

An internal attacker with valid administrative credentials can exploit Cisco ISE to take full control of the system. This access to critical network management allows the attacker to disrupt or disable all enterprise network connectivity.

2Halo Surface Signal

Denial of Service

External exposure likelihood

Halo Surface Signal score for CVE-2026-20147

Cisco ISE is an internal network policy management and access control appliance. Its administrative interface is designed for use within private network segments and is typically protected by internal access controls. Public internet exposure of such management surfaces is uncommon and requires specific, insecure configurations, aligning with an unlikely surface signal.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability in Cisco Identity Services Engine (ISE) allows an authenticated administrator to run unauthorized commands on the system, potentially gaining full control and causing denial of service. This is critical because an attacker with existing administrative access could exploit this to compromise the entire network.

  • Requires administrative credentials.
  • Can lead to full system compromise.
  • May disrupt network access for endpoints.

Attack Path

How an attacker could exploit the issue

An attacker with administrative credentials can exploit this vulnerability by sending a crafted HTTP request to an affected Cisco ISE or ISE-PIC device. This could allow them to gain user-level access to the underlying operating system and then elevate privileges to root, potentially leading to a denial of service.

  • Requires administrative credentials.
  • Exploitable via crafted HTTP requests.
  • Can lead to OS command execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability allows an authenticated, remote attacker to execute arbitrary commands on Cisco ISE devices, with the potential for privilege escalation. Exploitation requires valid administrative credentials and sending a crafted HTTP request. Successful exploitation could lead to a denial of service in single-node deployments, impacting network access for unauthenticated endpoints.

  • Exploitation requires admin credentials.
  • No public exploit code reported.
  • Cisco has released an advisory.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

Prioritize immediate patching of Cisco ISE and ISE-PIC devices if they are exposed to administrative access from untrusted networks. Given the critical nature and potential for remote code execution, any exposure of administrative interfaces to the internet, or even broad internal network segments, constitutes a high-risk scenario requiring prompt mitigation.

  • Apply Cisco security advisory patch.
  • Isolate affected appliances from untrusted networks.
  • Monitor for anomalous administrative login attempts.

Frequently asked questions

What is Cisco Identity Services Engine (ISE) and its role in network security?

Cisco Identity Services Engine (ISE) is a network security solution that provides policy enforcement, access control, and guest access management. It helps control which users and devices can connect to a network and what actions they are permitted to perform. Cisco ISE-PIC is a related component involved in policy enforcement.

What is the weakness class for CVE-2026-20147 and what does it mean?

The weakness class for CVE-2026-20147 is CWE-77, which signifies 'Improper Neutralization of Special Elements used in an OS Command (OS Command Injection)'. This means the software does not adequately process special characters or commands, potentially allowing an attacker to inject and execute operating system commands.

How can an attacker exploit CVE-2026-20147 and what is the scope of impact?

An attacker with administrative credentials can exploit this vulnerability by sending a specially crafted HTTP request to an affected Cisco ISE or ISE-PIC device. This exploit could grant the attacker user-level access to the underlying operating system, enabling privilege escalation to root. In single-node ISE deployments, a successful exploit might cause a denial of service, preventing unauthenticated endpoints from accessing the network until the device is restored.

What is the relevance of CVE-2026-20147, considering its surface signal?

Cisco ISE is an appliance for internal network policy and access control, typically accessed within private network segments and protected by internal security measures. Public internet exposure of its administrative interface is unusual and suggests a specific, insecure configuration. The Halo Surface Signal indicates this scenario is unlikely due to the inherent nature of Cisco ISE and its intended use, suggesting that exploitation would likely require a misconfiguration or intentional exposure.

What practical steps should be taken to mitigate CVE-2026-20147?

Organizations using Cisco ISE and ISE-PIC should prioritize applying the patches recommended in the Cisco security advisory. It is crucial to isolate affected appliances from untrusted networks and monitor for any suspicious administrative login attempts. Given the critical nature of this vulnerability and the potential for remote code execution, any administrative interface exposure to the internet or broadly accessible internal segments presents a high-risk scenario that demands immediate attention.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished Modified