CVE-2025-20303 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 validation and neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious JavaScript code into specific pages of the interface. The attack vector requires the attacker to have at least a low-privileged authenticated account on the affected device, and user interaction is necessary to trigger the malicious script execution. Upon successful exploitation, the attacker can execute arbitrary scripts within the security context of the web interface, potentially stealing session cookies, hijacking user sessions, or accessing sensitive browser-based information. The vulnerability affects a broad range of Cisco ISE versions from 3.1.0 through 3.4 Patch 3, indicating a long-standing issue across multiple releases. The CVSS v3.1 base score is 5.4 (medium severity), reflecting network attack vector, low attack complexity, low privileges required, and user interaction needed. The scope is changed (S:C), indicating that exploitation could affect resources beyond the vulnerable component. No public exploits are currently known, but the presence of this vulnerability in a critical network access control product makes it a significant concern. Cisco ISE is widely deployed in enterprise and service provider environments to enforce security policies, making the management interface a high-value target for attackers seeking to escalate privileges or pivot within networks.

For European organizations, the impact of CVE-2025-20303 can be substantial due to the widespread use of Cisco ISE in securing network access and enforcing policy compliance. Successful exploitation could lead to unauthorized disclosure of sensitive session information, enabling attackers to hijack administrative sessions or escalate privileges within the management interface. This compromises the confidentiality and integrity of network access controls, potentially allowing attackers to manipulate authentication and authorization policies. While availability is not directly impacted, the indirect effects of compromised management interfaces could disrupt network security operations. Organizations in sectors such as finance, telecommunications, government, and critical infrastructure are particularly at risk, as they rely heavily on Cisco ISE for secure network segmentation and access control. The requirement for low-privileged authentication reduces the attack surface but does not eliminate risk, especially in environments with many users or weak credential management. The need for user interaction limits automated exploitation but targeted phishing or social engineering attacks could facilitate triggering the vulnerability. Overall, the vulnerability poses a moderate risk to European entities, warranting prompt remediation to prevent lateral movement and data breaches.

1. Apply Cisco's security patches and updates for Cisco ISE versions affected by CVE-2025-20303 as soon as they become available to remediate the vulnerability. 2. Restrict access to the Cisco ISE management interface to trusted administrative networks and enforce strong multi-factor authentication (MFA) to reduce the risk of low-privileged account compromise. 3. Implement strict input validation and output encoding on all user-supplied data within the management interface to prevent injection of malicious scripts. 4. Monitor and audit user activities on the Cisco ISE interface for unusual or unauthorized actions that may indicate exploitation attempts. 5. Educate administrators and users about phishing and social engineering risks to minimize the likelihood of user interaction triggering reflected XSS attacks. 6. Employ web application firewalls (WAFs) with rules tuned to detect and block reflected XSS payloads targeting the Cisco ISE interface. 7. Regularly review and minimize the number of users with access to the management interface, enforcing the principle of least privilege. 8. Conduct periodic security assessments and penetration testing focused on the management interface to identify and remediate similar injection vulnerabilities proactively.