CVE-2026-76446 in Identity Services Engine Software
Summary
by MITRE • 09/16/2026
A vulnerability in an API of Cisco ISE and Cisco ISE-PIC could allow an authenticated, remote attacker to read specific files on the underlying operating system of an affected device.
This vulnerability is due to improper restriction of XML external entity references. An attacker could exploit this vulnerability by sending a crafted request to an affected device. A successful exploit could allow the attacker to read specific files on the affected system that the underlying process has permission to access.
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Analysis
by VulDB Data Team • 09/16/2026
The identified security flaw resides within the application programming interface of Cisco Identity Services Engine and its associated Policy Information Card component, presenting a significant risk to network infrastructure integrity. This vulnerability stems from an improper restriction of XML external entity references, a class of issues commonly categorized under CWE-611 in industry standard classification systems. The core technical deficiency lies in the system's failure to adequately sanitize or validate input data before processing it as part of an Extensible Markup Language document. When an authenticated user submits a request containing specially crafted XML content, the underlying parser processes external entity definitions without sufficient safeguards against unauthorized resource access. This lack of validation allows the application to resolve and retrieve arbitrary file paths specified within the malicious payload, effectively bypassing intended security controls that should restrict such operations to authorized internal resources only.
The operational impact of this vulnerability is substantial for organizations relying on Cisco ISE for network access control and policy enforcement. An authenticated remote attacker can leverage this flaw to read specific files from the underlying operating system hosting the affected device. The scope of accessible data is limited by the permissions granted to the process executing the vulnerable API endpoint, meaning that if the service runs with elevated privileges or has broad file system access, the potential for data exfiltration increases significantly. Attackers could target configuration files containing sensitive credentials, database connection strings, private keys, or other critical system artifacts. This capability transforms a simple authentication bypass into a full-scale information disclosure event, potentially compromising not only the specific device but also any downstream systems that rely on secrets stored within those accessible files.
From an offensive security perspective, this vulnerability aligns with techniques observed in the MITRE ATT&CK framework, specifically relating to Command and Control mechanisms involving data staging or exfiltration over alternative protocols such as XML-based interfaces. The exploitation vector requires prior authentication, which necessitates that the attacker has valid credentials for the affected service. This constraint limits the attack surface to insider threats or compromised accounts but does not diminish the severity of the potential damage once access is established. The ability to read arbitrary files can serve as a stepping stone for further lateral movement within the network environment, allowing adversaries to gather intelligence on other systems and services connected through the Identity Services Engine infrastructure.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Cisco has released software updates that address this improper restriction of XML external entity references by implementing stricter input validation and disabling unnecessary XML features such as external entity resolution where not explicitly required for business functionality. Administrators should apply these patches promptly to close the exposure window. In addition to patching, organizations should enforce strict access controls on API endpoints, ensuring that only necessary roles have permission to interact with vulnerable interfaces. Implementing web application firewalls can also provide an additional layer of defense by detecting and blocking malformed XML requests or known attack patterns associated with XXE exploitation before they reach the application logic. Regular auditing of authentication logs and file system access events will aid in identifying any potential unauthorized attempts to exploit this vulnerability, ensuring that detection capabilities are aligned with the specific risks posed by information disclosure attacks.