CVE-2026-20147

CriticalRCE

Published: 15 April 2026

Published

15 April 2026

Modified

17 April 2026

KEV Added

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Patch

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CVSS Score 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS Score 0.0032 55.2th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-20147 is a critical-severity Command Injection (CWE-77) vulnerability in Cisco ISE (inferred from references). Its CVSS base score is 9.9 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation of Remote Services (T1210); ranked in the top 44.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploitation of Remote Services (T1210) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Directly addresses the root cause of command injection by requiring validation of user-supplied input in crafted HTTP requests to the Cisco ISE device.

SI-2 Flaw Remediation good match

prevent

Mandates timely identification, reporting, and remediation of flaws like this input validation vulnerability through patching as recommended in the Cisco advisory.

AC-6 Least Privilege partial match

prevent

Enforces least privilege to limit administrative access and mitigate damage from privilege escalation to root following initial exploitation.

MITRE ATT&CK Enterprise TechniquesAI

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1059.004 Unix Shell Execution

Adversaries may abuse Unix shell commands and scripts for execution.

attack.mitre.org →

Why these techniques?

Command injection (CWE-77) in Cisco ISE web interface enables authenticated remote arbitrary OS command execution (T1210: Exploitation of Remote Services; T1059.004: Unix Shell), with privilege escalation and DoS potential.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

A vulnerability in Cisco ISE and Cisco ISE-PIC could allow an authenticated, remote attacker to execute arbitrary commands on the underlying operating system of an affected device. To exploit this vulnerability, the attacker must have valid administrative credentials. This vulnerability…

is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to obtain user-level access to the underlying operating system and then elevate privileges to root. In single-node ISE deployments, successful exploitation of this vulnerability could cause the affected ISE node to become unavailable, resulting in a denial of service (DoS) condition. In that condition, endpoints that have not already authenticated would be unable to access the network until the node is restored.

Deeper analysisAI

CVE-2026-20147 is a high-severity vulnerability affecting Cisco Identity Services Engine (ISE) and Cisco ISE-PIC. It stems from insufficient validation of user-supplied input, classified under CWE-77 (Command Injection), with a CVSS v3.1 base score of 9.9 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H). Published on April 15, 2026, the flaw enables an authenticated, remote attacker possessing valid administrative credentials to execute arbitrary commands on the underlying operating system of an affected device by sending a crafted HTTP request.

An attacker with administrative privileges can exploit this vulnerability over the network with low complexity and no user interaction required. Successful exploitation grants initial user-level access to the operating system, followed by privilege escalation to root. In single-node ISE deployments, it can additionally trigger a denial-of-service (DoS) condition, rendering the node unavailable and preventing unauthenticated endpoints from accessing the network until restoration.

The official Cisco Security Advisory provides details on mitigation strategies and available patches; refer to https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-rce-traversal-8bYndVrZ for remediation guidance.