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 software. The root cause is improper neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious JavaScript code into specific pages of the interface. This vulnerability requires the attacker to be authenticated with at least low-privileged access to the device, which means the attacker must have valid credentials but does not need administrative privileges. Upon successful exploitation, the attacker can execute arbitrary scripts in the victim's browser session when they access the affected interface pages. This can lead to theft of sensitive browser-based information such as session tokens or credentials, and potentially allow further attacks like session hijacking or privilege escalation. The vulnerability affects a broad range of Cisco ISE versions from 3.1.0 through 3.4 Patch 2, indicating a long window of exposure. The CVSS v3.1 base score is 4.8 (medium severity), reflecting network attack vector, low attack complexity, high privileges required, user interaction needed, and impact limited to confidentiality and integrity. No public exploits are known at this time, but the vulnerability poses a risk especially in environments where multiple users have low-level access to the management interface. Cisco ISE is widely deployed in enterprise networks for identity and access management, making this vulnerability relevant for organizations relying on Cisco for network policy enforcement and security.

For European organizations, this vulnerability could lead to unauthorized disclosure of sensitive information within the Cisco ISE management interface, such as session tokens or user credentials, if exploited. This can undermine the integrity of network access controls and potentially allow attackers to escalate privileges or move laterally within the network. Given Cisco ISE’s role in enforcing security policies and authenticating devices, exploitation could weaken overall network security posture. Industries with stringent compliance requirements, such as finance, healthcare, and critical infrastructure, may face regulatory and operational risks if this vulnerability is exploited. The requirement for authenticated access limits the attack surface but insider threats or compromised low-privileged accounts could be leveraged. The reflected XSS nature also requires user interaction, which may reduce automated exploitation but does not eliminate risk from targeted phishing or social engineering attacks. The broad range of affected versions means many organizations may be vulnerable if patches are not applied promptly.

European organizations should immediately verify if their Cisco ISE deployments run affected versions (3.1.0 through 3.4 Patch 2) and prioritize patching once Cisco releases fixes. Until patches are applied, restrict access to the Cisco ISE web interface to trusted administrators and limit low-privileged user accounts to the minimum necessary. Implement strict network segmentation and access controls to reduce exposure of the management interface. Employ multi-factor authentication (MFA) for all users accessing Cisco ISE to reduce risk from compromised credentials. Monitor logs for unusual activity indicating attempted exploitation or unauthorized access. Educate users with access about phishing and social engineering risks that could trigger reflected XSS attacks. Consider deploying web application firewalls (WAFs) with rules to detect and block reflected XSS payloads targeting Cisco ISE interfaces. Regularly review and audit user privileges to ensure no unnecessary low-privileged accounts exist. Finally, stay informed on Cisco advisories for patches and updated mitigation guidance.