CVE-2025-34318 is a stored cross-site scripting (XSS) vulnerability identified in IPFire, an open-source firewall distribution widely used for network security. The flaw exists in versions prior to 2.29 (Core Update 198) and is triggered when an authenticated user adds a new DNS entry via the web interface. Specifically, the vulnerability affects the parameters TLS_HOSTNAME, UPSTREAM_USER, UPSTREAM_PASSWORD, ADMIN_MAIL_ADDRESS, and ADMIN_PASSWORD submitted in an HTTP POST request to /cgi-bin/dns.cgi. These parameters are stored and later rendered in the web interface without proper sanitization or encoding, allowing malicious JavaScript code to execute in the context of other users who view the DNS configuration page. This improper neutralization of input during web page generation corresponds to CWE-79. The attack requires the attacker to have authenticated access to the IPFire management interface and involves user interaction to add malicious DNS entries. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N) indicates network attack vector, low attack complexity, no privileges required beyond authenticated user, and user interaction needed. The vulnerability can lead to session hijacking, unauthorized actions, or theft of sensitive information from administrative users. Although no known exploits are currently reported in the wild, the presence of stored XSS in a security appliance's management interface poses a significant risk. The lack of available patches at the time of reporting necessitates immediate mitigation efforts by administrators.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on IPFire as a critical component of their network security infrastructure. Successful exploitation could allow attackers to execute arbitrary scripts within the administrative interface, potentially leading to session hijacking, theft of credentials, or unauthorized changes to firewall and DNS configurations. This undermines the confidentiality and integrity of network security settings and could facilitate further lateral movement or data exfiltration. Given IPFire’s role in perimeter defense, compromise could expose internal networks to external threats. The requirement for authenticated access limits the attack surface but does not eliminate risk, as insider threats or compromised credentials could be leveraged. The medium severity rating reflects the balance between impact and exploitation complexity, but the strategic importance of firewall appliances in European critical infrastructure and enterprises elevates the practical risk. Organizations in sectors such as finance, government, telecommunications, and critical infrastructure are particularly vulnerable to the consequences of such an attack.

To mitigate this vulnerability, European organizations should immediately upgrade IPFire installations to version 2.29 (Core Update 198) or later once available, as this will include the necessary input sanitization fixes. Until patches are applied, administrators should restrict access to the IPFire web interface to trusted networks and users only, employing network segmentation and VPNs to limit exposure. Implement multi-factor authentication (MFA) for all administrative accounts to reduce the risk of credential compromise. Regularly audit DNS entries and firewall configurations for suspicious or unauthorized changes. Employ web application firewalls (WAFs) or intrusion detection systems (IDS) capable of detecting and blocking XSS payloads targeting the management interface. Educate administrators about the risks of stored XSS and the importance of cautious input handling. Finally, monitor IPFire logs and network traffic for anomalous activities that could indicate exploitation attempts.