CVE-2025-20235 is a cross-site scripting (XSS) vulnerability found in the web-based management interface of Cisco Secure Firewall Management Center (FMC) software. This vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing an unauthenticated remote attacker to inject malicious scripts into the interface. The attacker can exploit this by submitting crafted input into various data fields within the affected interface. When a legitimate user accesses the compromised interface, the malicious script executes in the context of the user's browser session. This can lead to unauthorized access to sensitive browser-based information, session hijacking, or manipulation of the interface's content. The vulnerability affects a wide range of Cisco FMC versions, spanning multiple releases from 6.2.3 through 7.4.2.2, indicating a long-standing issue across many deployed versions. The CVSS v3.1 base score is 6.1 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), scope changed (S:C), and low impact on confidentiality and integrity but no impact on availability. No known exploits in the wild have been reported as of the publication date (August 14, 2025). The vulnerability is significant because Cisco FMC is a critical security management platform used to configure and monitor Cisco Secure Firewalls, making it a high-value target for attackers aiming to compromise network defenses or steal sensitive security data.

For European organizations, this vulnerability poses a risk to the confidentiality and integrity of firewall management operations. Successful exploitation could allow attackers to execute arbitrary scripts in the context of the management interface, potentially leading to session hijacking, theft of administrative credentials, or manipulation of firewall policies. This could degrade the security posture of affected organizations, enabling further network intrusion or data exfiltration. Given Cisco FMC's widespread use in enterprise and government sectors across Europe, exploitation could disrupt critical infrastructure protection and sensitive data security. The requirement for user interaction (clicking a malicious link or visiting a crafted page) somewhat limits the attack vector but does not eliminate risk, especially in environments where administrators frequently access the management interface. The scope change in the CVSS vector indicates that the vulnerability can affect resources beyond the vulnerable component, amplifying potential damage. Although no exploits are currently known in the wild, the broad version impact and the critical role of FMC in network security management make this a vulnerability that European organizations must address promptly to avoid targeted attacks.

1. Immediate patching: Organizations should monitor Cisco's official advisories and apply patches or updates as soon as they become available for the affected FMC versions. 2. Input validation enhancements: Until patches are applied, implement web application firewalls (WAFs) or reverse proxies with rules designed to detect and block suspicious input patterns targeting the FMC interface. 3. Restrict access: Limit access to the FMC management interface to trusted networks and IP addresses using network segmentation and firewall rules to reduce exposure to unauthenticated remote attackers. 4. User training: Educate administrators on the risks of clicking unknown or suspicious links, especially when logged into the FMC interface, to reduce the likelihood of successful user interaction exploitation. 5. Multi-factor authentication (MFA): Although the vulnerability does not require authentication, enforcing MFA on the FMC interface can reduce the impact of session hijacking or credential theft. 6. Monitoring and logging: Enable detailed logging and monitor for unusual activity or access patterns on the FMC interface to detect potential exploitation attempts early. 7. Incident response readiness: Prepare incident response plans specific to FMC compromise scenarios to enable rapid containment and remediation if exploitation is detected.