CVE-2026-76424 in Identity Services Engine
Summary
by MITRE • 09/16/2026
A vulnerability in the REST API of Cisco ISE could allow an authenticated, remote attacker to upload or copy arbitrary files on an affected device.
This vulnerability is due to insufficient validation in file operations. An attacker could exploit this vulnerability by uploading a file with a crafted path. A successful exploit could allow the attacker to upload files to arbitrary locations and execute arbitrary commands as root on the affected device. To exploit this vulnerability, the attacker must have valid administrative credentials.
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Analysis
by VulDB Data Team • 09/16/2026
The identified security flaw resides within the REST API implementation of Cisco Identity Services Engine (ISE), specifically affecting file operation endpoints that handle uploads or copies. This vulnerability stems from insufficient validation mechanisms when processing user-supplied input related to file paths. The core technical deficiency lies in the application's failure to properly sanitize or canonicalize directory traversal sequences, such as dot-dot-slash characters, within the path parameters provided by the client. Consequently, an authenticated attacker can manipulate these inputs to redirect file operations outside of the intended sandboxed directories. This lack of strict boundary enforcement allows for arbitrary file placement on the underlying operating system filesystem, bypassing standard access controls that would normally restrict write permissions to specific application-specific folders.
From a threat modeling perspective, this vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory and CWE-94: Improper Control of Generation of Code (Code Injection). The exploitation vector requires the attacker to possess valid administrative credentials for the Cisco ISE platform. This prerequisite significantly limits the attack surface compared to unauthenticated exploits, as it necessitates prior compromise or theft of high-level privileges. However, once an attacker obtains these credentials through social engineering, credential stuffing, or other means, they can interact with the REST API endpoints directly. By crafting HTTP requests that include maliciously constructed file paths in the upload or copy operations, the attacker can write files to critical system directories such as /etc, /usr/bin, or other locations where execution privileges are granted to the root user or services running under elevated permissions.
The operational impact of this vulnerability is severe, effectively resulting in full remote code execution with root-level privileges on the affected device. Cisco ISE serves as a central component in many enterprise networks, handling authentication, authorization, and accounting for network access control systems like NAC (Network Access Control). Compromising an ISE node grants attackers complete control over its configuration and underlying operating system. This can lead to the manipulation of security policies, allowing unauthorized devices to gain network access or blocking legitimate users from connecting. Furthermore, because ISE often integrates with other identity providers such as Active Directory or LDAP servers, a compromised instance could be used to pivot attacks into broader corporate infrastructure. Attackers may deploy backdoors, exfiltrate sensitive authentication logs containing user credentials and session tokens, or modify system binaries to maintain persistent access even if the initial vulnerability is patched.
This scenario maps directly to several techniques within the MITRE ATT&CK framework. The ability to upload arbitrary files corresponds to T1105: Ingress Tool Transfer, while writing to sensitive directories for execution aligns with T1059: Command and Scripting Interpreter or potentially T1204: User Execution if social engineering is involved in triggering the payload. The requirement for administrative credentials places this within the context of Initial Access techniques such as T1078: Valid Accounts, indicating that robust identity management practices are critical to mitigating this risk.
Mitigation strategies must focus on both immediate remediation and long-term defense-in-depth measures. Cisco has released software updates addressing this specific flaw; therefore, applying the latest recommended patches for Cisco ISE is the primary corrective action. Administrators should verify their current version against Cisco’s security advisories to ensure they are running a patched release. In addition to patching, organizations must enforce strict access controls on administrative accounts. This includes implementing multi-factor authentication (MFA) for all privileged users to reduce the likelihood of credential compromise. Network segmentation is also crucial; management interfaces and REST API endpoints should be isolated from general user traffic and accessible only through secure, monitored channels such as VPNs or jump hosts with rigorous logging enabled. Regular auditing of administrative login attempts and file system changes can help detect exploitation activities early. Finally, principle of least privilege should be applied to service accounts used by the ISE application itself, ensuring that even if an attacker gains access via the API, they do not automatically inherit root-level permissions without additional lateral movement steps.