CVE-2025-20267 is a medium-severity vulnerability affecting Cisco Identity Services Engine (ISE) software versions ranging from 3.0.0 through various patches up to 3.4.0. The vulnerability is a reflected cross-site scripting (XSS) flaw in the web-based management interface of Cisco ISE. It arises from insufficient validation and improper neutralization of user-supplied input, specifically script-related HTML tags, allowing an authenticated remote attacker with valid administrative credentials to inject malicious script code into the interface. Successful exploitation enables the attacker to execute arbitrary JavaScript in the context of the victim's browser session when interacting with the management interface. This can lead to unauthorized actions within the interface, theft of sensitive browser-based information such as session tokens or credentials, and potentially facilitate further attacks like session hijacking or privilege escalation within the management console. The vulnerability requires high privileges (administrative access) and user interaction (the victim must access the maliciously crafted page or interface element). The CVSS v3.1 base score is 4.8, reflecting a medium severity due to the need for authentication and user interaction, but with network attack vector and low attack complexity. No known exploits are currently reported in the wild, and no patches or mitigation links were provided in the source data at the time of publication.

For European organizations, this vulnerability poses a risk primarily to the security and integrity of network access control and policy enforcement managed via Cisco ISE. Since Cisco ISE is widely used in enterprise environments for identity and access management, exploitation could allow attackers with administrative credentials to execute malicious scripts, potentially leading to session hijacking, unauthorized changes in network policies, or leakage of sensitive configuration data. This could disrupt network security posture, enabling lateral movement or data exfiltration. The impact is heightened in sectors with stringent compliance requirements such as finance, healthcare, and critical infrastructure, where Cisco ISE is often deployed. However, the requirement for valid administrative credentials and user interaction limits the attack surface to insiders or attackers who have already compromised an admin account, reducing the likelihood of widespread exploitation but increasing the risk of targeted attacks within organizations.

European organizations should prioritize the following specific mitigations: 1) Immediately audit and restrict administrative access to Cisco ISE management interfaces, enforcing strong multi-factor authentication (MFA) to reduce the risk of credential compromise. 2) Monitor and review administrative user activity logs for suspicious behavior indicative of credential misuse or attempted XSS exploitation. 3) Apply the latest Cisco ISE software updates and patches as soon as Cisco releases fixes addressing this vulnerability. 4) Implement Content Security Policy (CSP) headers and other browser-based mitigations to limit the impact of potential XSS payloads. 5) Conduct regular security training for administrators to recognize phishing or social engineering attempts that could lead to credential theft. 6) Segment the management interface network to restrict access only to trusted administrative hosts and networks. 7) Employ web application firewalls (WAFs) with rules tuned to detect and block XSS payloads targeting the Cisco ISE interface. These measures collectively reduce the risk of exploitation and limit the potential damage from successful attacks.