CVE-2026-20282 in Identity Services Engine
Summary
by MITRE • 09/17/2026
A vulnerability in Cisco ISE could allow an authenticated, remote attacker to obtain write access on the underlying operating system of an affected device.
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 write access to the underlying operating system. To exploit this vulnerability, the attacker must have valid administrative credentials. Note: For CVE-2026-20282, Cisco has assigned a Security Impact Rating (SIR) of High rather than Medium as the score indicates. The reason is that it is easy to get to root from the achieved privilege level.
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Analysis
by VulDB Data Team • 09/21/2026
The vulnerability identified in Cisco Identity Services Engine allows an authenticated remote attacker to escalate privileges and obtain write access to the underlying operating system. This flaw stems from insufficient validation of user-supplied input within the application layer, specifically when processing HTTP requests. Although exploitation requires valid administrative credentials, which limits the attack surface compared to unauthenticated exploits, the severity is significantly amplified by the ease with which an attacker can transition from the achieved privilege level to root access on the host system. Cisco has assigned a Security Impact Rating of High to this issue, reflecting the critical nature of gaining write access to the operating system rather than merely disrupting service or reading data.
From a technical perspective, the core weakness lies in the application's failure to properly sanitize or validate inputs before they are processed by underlying system commands or file operations. This lack of rigorous input validation enables an attacker to inject malicious payloads via crafted HTTP requests that bypass intended security controls. Once these payloads execute within the context of the service, they leverage existing privilege escalation paths on the operating system to gain write permissions at the root level. The ability to modify files and configurations at this depth allows for persistent compromise, potential installation of backdoors, or complete control over the identity management infrastructure managed by Cisco ISE.
The operational impact of this vulnerability is severe due to the central role that Identity Services Engine plays in network security architectures. As a platform responsible for authentication, authorization, and accounting, compromising its underlying operating system grants an attacker comprehensive visibility into user credentials, network policies, and access logs. An adversary with root-level write access can alter configuration files to disable security controls, create new administrative accounts, or modify logging mechanisms to cover their tracks. This effectively neutralizes the primary defense mechanism of the organization's identity management strategy, potentially leading to widespread unauthorized access across the enterprise network.
This vulnerability aligns with Common Weakness Enumeration category CWE-20 Improper Input Validation and is consistent with ATT&CK techniques related to Privilege Escalation such as T1068 Exploitation for Privilege Escalation and T1543 Create or Modify System Process. Mitigation strategies should prioritize the immediate application of vendor-provided patches that address the input validation logic in the affected software versions. In addition to patching, organizations should enforce strict network segmentation policies to restrict access to Cisco ISE management interfaces only from trusted administrative subnets. Implementing multi-factor authentication for all administrative accounts and monitoring HTTP request logs for anomalous patterns can further reduce the risk of exploitation by adding layers of defense against credential-based attacks that attempt to leverage this specific input validation flaw.