CVE-2026-20305 in Identity Services Engine Software
Summary
by MITRE • 09/17/2026
A vulnerability in the diagnostic tools of Cisco ISE and ISE-PIC could allow an authenticated, remote attacker to perform command injection attacks on the underlying operating system and elevate privileges to root. To exploit this vulnerability, the attacker must have valid administrative credentials.
This vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by sending crafted commands to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and elevate privileges to root. In single-node 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.
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Analysis
by VulDB Data Team • 09/17/2026
The identified security flaw resides within the diagnostic utilities of Cisco Identity Services Engine and its associated PIC component, presenting a critical risk vector for organizations relying on these systems for network access control and policy enforcement. The core technical deficiency stems from improper validation of user-supplied input passed to underlying operating system commands via the web-based management interface. This lack of rigorous sanitization allows an authenticated attacker with valid administrative credentials to inject arbitrary shell commands into the diagnostic processes. Because the affected services typically operate with elevated privileges, successful exploitation results in command injection that grants the attacker full control over the host operating system, effectively elevating their access level to root.
The operational impact of this vulnerability is severe and multifaceted, extending beyond mere unauthorized access to include significant service disruption. In single-node deployments, which are common in smaller or branch office environments lacking high-availability clustering, a successful exploit can destabilize the underlying operating system sufficiently to cause the ISE node to become unavailable. This leads directly to a denial of service condition where the authentication infrastructure ceases to function. Consequently, endpoints that have not yet completed their authentication process will be unable to gain network access until the compromised or crashed node is restored and secured. This disruption can halt business operations dependent on secure network connectivity and expose the organization to further risk if attackers use the initial foothold for lateral movement within the internal network.
From a classification perspective, this vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The attack vector is classified under ATT&CK technique T1059 Command and Scripting Interpreter, specifically leveraging command injection to execute arbitrary code. Furthermore, the requirement for valid administrative credentials places this within the context of privilege escalation following initial access via compromised high-privilege accounts. Mitigation strategies must prioritize immediate patching using vendor-provided updates that address the input validation flaws in the diagnostic tools. In environments where patching is not immediately feasible, network segmentation should be enforced to restrict management interface access strictly to trusted administrative subnets. Additionally, implementing strict role-based access control and multi-factor authentication for administrative accounts can reduce the likelihood of credential compromise leading to exploitation. Regular auditing of administrative activity logs is also recommended to detect any unauthorized attempts to interact with diagnostic endpoints.