CVE-2025-20331 is a medium-severity vulnerability affecting multiple versions of Cisco Identity Services Engine (ISE) software, including versions from 2.7.0 p8 through 3.4.0 and various patches. The vulnerability arises from improper neutralization of script-related HTML tags in the web-based management interface of Cisco ISE and Cisco ISE-PIC. Specifically, the interface does not sufficiently validate user-supplied input, allowing an authenticated attacker with at least low-privileged access to inject malicious scripts into the interface. This stored cross-site scripting (XSS) vulnerability enables the attacker to execute arbitrary JavaScript code in the context of the victim user's browser session when they access the affected interface pages. Successful exploitation could lead to unauthorized access to sensitive browser-based information, session hijacking, or manipulation of the interface's behavior. The attack requires the attacker to have valid credentials with low privileges, and user interaction is necessary for the malicious script to execute (e.g., the victim must view the compromised page). The vulnerability has a CVSS v3.1 base score of 5.4, reflecting its medium severity, with attack vector as network, low attack complexity, privileges required as low, user interaction required, and scope changed due to potential impact beyond the vulnerable component. No known exploits in the wild have been reported to date, and no official patches or mitigation links were provided in the source information. Given Cisco ISE's role as a critical network access control and policy management system, exploitation could undermine network security posture by compromising administrative sessions or leaking sensitive information.

For European organizations, the impact of CVE-2025-20331 could be significant due to the widespread use of Cisco ISE in enterprise and governmental networks for identity and access management. Successful exploitation could allow attackers to escalate privileges indirectly by stealing session tokens or credentials from administrators or operators managing the network access policies. This could lead to unauthorized network access, policy manipulation, or lateral movement within the network. Confidentiality is primarily at risk, with potential integrity impacts if attackers modify configurations via hijacked sessions. Availability impact is minimal as the vulnerability does not directly enable denial-of-service. The requirement for low-privileged authentication limits the attack surface but does not eliminate risk, especially in environments with many users having access to the management interface. European organizations in sectors such as finance, telecommunications, critical infrastructure, and government are particularly sensitive due to regulatory requirements like GDPR and the critical nature of network security. The vulnerability could also be leveraged in targeted attacks or espionage campaigns given the strategic importance of network access control systems.

To mitigate CVE-2025-20331, European organizations should: 1) Immediately audit and restrict access to the Cisco ISE management interface, ensuring only trusted and necessary personnel have low-privileged accounts, and enforce strong authentication mechanisms such as multi-factor authentication (MFA). 2) Monitor and review user input fields in the management interface for suspicious or anomalous entries that could indicate attempted script injection. 3) Implement strict Content Security Policy (CSP) headers on the Cisco ISE web interface to reduce the impact of injected scripts. 4) Regularly update Cisco ISE to the latest available versions or patches once Cisco releases fixes addressing this vulnerability. 5) Conduct security awareness training for administrators to recognize phishing or social engineering attempts that could facilitate credential compromise. 6) Employ network segmentation and monitoring to detect unusual administrative activity or lateral movement originating from compromised accounts. 7) Use web application firewalls (WAFs) with custom rules to detect and block common XSS payloads targeting the Cisco ISE interface. These measures, combined, reduce the likelihood of exploitation and limit potential damage.