CVE-2025-20289 is a reflected Cross-Site Scripting (XSS) vulnerability found in the web-based management interface of Cisco Identity Services Engine (ISE) and Cisco ISE-PIC. The root cause is insufficient input validation of user-supplied data within specific pages of the interface, allowing an authenticated attacker with at least low-level privileges to inject malicious JavaScript code. When a legitimate user accesses the crafted page, the injected script executes in their browser context, potentially leading to session hijacking, theft of sensitive information such as cookies or tokens, or unauthorized actions within the management interface. The vulnerability spans multiple versions of Cisco ISE, specifically versions 3.1.0 through 3.4 Patch 2, including various patches and point releases. The attack vector is network-based, requiring the attacker to be authenticated (low privilege) and to trick a user into interacting with the maliciously crafted interface page. The CVSS 3.1 score of 4.8 reflects a medium severity, considering the attack complexity is low, but privileges and user interaction are required. No public exploits or active exploitation have been reported to date. Cisco ISE is widely used for network access control, policy enforcement, and identity management, making this vulnerability significant for organizations relying on it for secure network operations.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Cisco ISE for network access control, policy enforcement, and identity management. Successful exploitation could lead to unauthorized disclosure of sensitive session information, enabling attackers to impersonate legitimate users or administrators, potentially leading to further compromise of network resources. This could disrupt network security policies, allow lateral movement within the network, or expose confidential data. Given the widespread use of Cisco ISE in enterprise and critical infrastructure environments across Europe, the vulnerability poses a risk to sectors such as finance, telecommunications, healthcare, and government. The requirement for authentication and user interaction limits the attack scope but does not eliminate risk, particularly in environments with many users or where phishing/social engineering could be leveraged. The reflected XSS could also be used as a stepping stone for more complex attacks targeting network management and security controls.

1. Apply the latest Cisco patches and updates for Cisco ISE as soon as they become available, prioritizing affected versions from 3.1.0 through 3.4 Patch 2. 2. Restrict access to the Cisco ISE web management interface to trusted administrators only, using network segmentation and firewall rules to limit exposure. 3. Enforce strong authentication mechanisms, including multi-factor authentication (MFA), to reduce the risk of low-privileged account compromise. 4. Educate users and administrators about phishing and social engineering risks that could facilitate exploitation via user interaction. 5. Monitor web interface logs and network traffic for unusual or suspicious activity indicative of attempted XSS exploitation. 6. Consider implementing Content Security Policy (CSP) headers and other web security controls on the management interface to mitigate the impact of injected scripts. 7. Regularly audit user privileges and remove unnecessary low-privileged accounts to reduce the attack surface. 8. Use web application firewalls (WAFs) where possible to detect and block malicious input patterns targeting the management interface.