CVE-2025-34315 is a stored cross-site scripting (XSS) vulnerability affecting IPFire, an open-source firewall distribution widely used for network security. The flaw exists in versions prior to 2.29 (Core Update 198) within the web interface component that manages remote syslog server configurations. Specifically, when an authenticated user updates the remote syslog server address, the input is sent via an HTTP POST request to /cgi-bin/logs.cgi/config.dat with the REMOTELOG_ADDR parameter. This parameter's value is stored without proper sanitization or encoding and later rendered in the web interface. Because of this improper neutralization of input (CWE-79), malicious JavaScript code injected into REMOTELOG_ADDR executes in the browsers of other users who access the configuration page. The vulnerability requires the attacker to be authenticated but does not require elevated privileges, making it feasible for any logged-in user to exploit. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, partial user interaction (viewing the page), and limited scope impact. The vulnerability can lead to session hijacking, credential theft, or unauthorized actions performed in the context of the victim user. Although no public exploits are currently known, the stored nature of the XSS makes it a persistent threat once exploited. IPFire is commonly deployed in enterprise and small-to-medium business environments, including in Europe, where it protects network perimeters and internal segments.

For European organizations, this vulnerability poses a risk to the confidentiality and integrity of administrative sessions and potentially sensitive network configuration data. An attacker with valid credentials could inject malicious scripts that execute in the browsers of other administrators or users with access to the IPFire web interface. This could lead to session hijacking, unauthorized configuration changes, or theft of credentials and sensitive information. Given IPFire's role as a firewall and security appliance, compromise could facilitate further network intrusion or disruption. The medium CVSS score reflects the moderate risk, considering the need for authentication and user interaction (viewing the page). However, the widespread use of IPFire in European SMEs and public sector organizations increases the potential impact. Additionally, the vulnerability could be leveraged as part of a broader attack chain targeting critical infrastructure or government networks, especially in countries with high IPFire adoption. The lack of known exploits in the wild currently limits immediate risk but does not preclude future exploitation.

European organizations should immediately upgrade IPFire installations to version 2.29 (Core Update 198) or later, where this vulnerability is addressed. If immediate patching is not possible, administrators should restrict access to the IPFire web interface to trusted networks and users only, employing network segmentation and VPNs. Implement strict authentication controls, including strong passwords and multi-factor authentication, to reduce the risk of unauthorized access. Regularly audit and monitor the remote syslog server configuration page for suspicious entries in the REMOTELOG_ADDR parameter. Employ Content Security Policy (CSP) headers on the IPFire web interface to limit the impact of potential XSS attacks. Educate administrators about the risks of stored XSS and encourage cautious handling of configuration inputs. Finally, maintain up-to-date backups of configuration data to enable recovery in case of compromise.