CVE-2025-4804 is a medium-severity vulnerability classified under CWE-79, which pertains to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This specific vulnerability affects WatchGuard Fireware OS versions from 12.0 through 12.11.1. The flaw exists within the spamBlocker module of the Fireware OS, allowing for stored XSS attacks. Stored XSS occurs when malicious input is saved by the application and later rendered in web pages without proper sanitization or encoding, enabling an attacker to execute arbitrary scripts in the context of the victim's browser. Exploitation of this vulnerability requires an authenticated administrator session on a locally managed Firebox device, meaning the attacker must already have high-level access to the device's management interface. The CVSS 4.0 base score is 4.8, reflecting a medium severity level, with attack vector being network-based but requiring high privileges (PR:H) and some user interaction (UI:P). The vulnerability does not impact confidentiality, integrity, or availability directly but could be leveraged to execute malicious scripts that may lead to session hijacking, credential theft, or further administrative actions if chained with other vulnerabilities. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that remediation may still be pending or in development. The vulnerability is limited in scope to the spamBlocker module and requires local administrative access, which reduces the risk of remote exploitation but still poses a threat in environments where administrative credentials or access are compromised or shared.

For European organizations using WatchGuard Fireware OS, particularly versions 12.0 through 12.11.1, this vulnerability poses a risk primarily to network security infrastructure. Firebox devices are often deployed as perimeter firewalls or unified threat management appliances, critical for protecting enterprise networks. Exploitation could allow an attacker with administrative access to execute malicious scripts within the management interface, potentially leading to session hijacking or unauthorized changes to firewall policies. This could undermine network defenses, allowing further lateral movement or data exfiltration. Although the vulnerability requires authenticated admin access, insider threats or compromised credentials could be leveraged by attackers. The impact is heightened in sectors with stringent regulatory requirements such as finance, healthcare, and critical infrastructure, where firewall integrity is paramount. Additionally, organizations with decentralized IT management or remote administration may face increased risk if local access controls are weak. The absence of known exploits reduces immediate risk, but the presence of this vulnerability in widely used security appliances necessitates prompt attention to prevent potential exploitation.

1. Restrict administrative access to Firebox devices strictly to trusted personnel and secure management networks using network segmentation and VPNs. 2. Enforce strong authentication mechanisms, including multi-factor authentication (MFA), for all administrator accounts to reduce the risk of credential compromise. 3. Regularly audit and monitor administrative sessions and logs for unusual activity that could indicate attempted exploitation. 4. Apply principle of least privilege by limiting the number of administrators and their permissions to only what is necessary. 5. Until an official patch is released, consider disabling or limiting the use of the spamBlocker module if feasible, or restrict its configuration changes to highly controlled environments. 6. Keep Fireware OS updated and subscribe to WatchGuard security advisories to promptly apply patches once available. 7. Conduct internal security awareness training to highlight risks associated with credential sharing and phishing that could lead to administrative access compromise. 8. Implement web application firewall (WAF) rules or intrusion detection systems (IDS) to detect anomalous web interface activity that may indicate exploitation attempts.