CVE-2025-20304 identifies multiple reflected cross-site scripting (XSS) vulnerabilities in the web-based management interface of Cisco Identity Services Engine (ISE) and Cisco ISE-PIC. These vulnerabilities arise from insufficient sanitization and validation of user-supplied input during web page generation, allowing an authenticated remote attacker with low privileges to inject malicious JavaScript code into specific interface pages. When a victim user accesses the crafted page, the injected script executes within their browser context, potentially enabling session hijacking, theft of sensitive information, or unauthorized actions within the management interface. The vulnerability affects a wide range of Cisco ISE versions from 3.1.0 through 3.4 Patch 3, covering multiple patch releases. Exploitation requires the attacker to have at least a low-privileged account on the device and user interaction to trigger the malicious payload. The CVSS v3.1 base score is 5.4 (medium), reflecting network attack vector, low attack complexity, low privileges required, and user interaction needed, with partial confidentiality and integrity impact but no availability impact. No public exploits are known at this time, but the vulnerability poses a risk to the confidentiality and integrity of management sessions and data. Cisco has not yet published patch links, indicating that mitigation may rely on configuration changes or upcoming updates. This vulnerability is particularly concerning for organizations relying on Cisco ISE for centralized network access control, as compromise of the management interface could lead to broader network security issues.

For European organizations, the exploitation of CVE-2025-20304 could lead to unauthorized disclosure of sensitive information managed through Cisco ISE, including network access policies and user credentials. Attackers could hijack sessions of administrators or other users, potentially escalating privileges or manipulating network access controls. This undermines the integrity of network security enforcement and could facilitate lateral movement or further compromise within enterprise networks. Given Cisco ISE's role in enforcing security policies and authenticating devices on corporate networks, successful exploitation could disrupt secure access, expose internal resources, and increase the risk of insider threats or external attacks. The requirement for low-privileged authentication reduces the attack surface but does not eliminate risk, especially in environments with many users having management interface access. The reflected XSS nature means social engineering or phishing could be used to trick users into triggering the exploit. European sectors with stringent regulatory requirements for data protection and network security, such as finance, healthcare, and critical infrastructure, face heightened risks from such vulnerabilities.

European organizations should immediately audit user accounts with access to Cisco ISE management interfaces and restrict privileges to the minimum necessary. Implement strict input validation and output encoding on all user-supplied data within the management interface where possible. Employ web application firewalls (WAFs) with custom rules to detect and block reflected XSS payloads targeting Cisco ISE URLs. Enforce multi-factor authentication (MFA) for all management interface users to reduce the risk of credential compromise. Monitor logs for unusual activity or repeated failed attempts indicative of exploitation attempts. Educate users with access to the interface about phishing risks and the importance of not clicking suspicious links. Segregate management interfaces from general user networks using network segmentation and access control lists (ACLs). Stay alert for Cisco security advisories and apply patches or updates promptly once released. Consider deploying browser security features such as Content Security Policy (CSP) headers if configurable on the interface to mitigate script injection impacts.