CVE-2023-29183 is a cross-site scripting (XSS) vulnerability identified in Fortinet's FortiProxy and FortiOS products, specifically affecting versions 6.2.0 through 7.2.4. The vulnerability arises from improper neutralization of input during web page generation in the GUI, particularly within the guest management settings. An authenticated attacker with low privileges can craft malicious input that, when processed by the vulnerable GUI, results in execution of arbitrary JavaScript code in the context of the victim's browser session. This can lead to session hijacking, unauthorized actions, or further exploitation such as privilege escalation or lateral movement within the network. The vulnerability requires the attacker to be authenticated and to trick a legitimate user into interacting with the malicious payload (user interaction). The CVSS v3.1 score of 7.3 reflects the high impact on confidentiality, integrity, and availability, combined with relatively low attack complexity and privileges required. No public exploits have been reported yet, but the vulnerability's nature and affected widely deployed Fortinet products make it a significant risk. FortiProxy and FortiOS are commonly used in enterprise environments for secure web gateway and firewall functionalities, making this vulnerability particularly concerning for organizations relying on these products for perimeter defense and secure access.

For European organizations, the impact of CVE-2023-29183 can be substantial. Successful exploitation can lead to unauthorized disclosure of sensitive information, manipulation or disruption of network security policies, and potential compromise of internal systems through session hijacking or further exploitation chains. Given Fortinet's widespread use in European enterprises, government agencies, and critical infrastructure sectors such as finance, telecommunications, and energy, this vulnerability could facilitate targeted attacks against high-value assets. The ability to execute unauthorized code within the management GUI could allow attackers to bypass security controls, alter configurations, or deploy persistent malware. This risk is heightened in environments where multi-factor authentication or strict network segmentation is not enforced. Additionally, the requirement for authentication means insider threats or compromised credentials could be leveraged to exploit this vulnerability, increasing the attack surface. The absence of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score underscores the urgency of addressing this issue.

To mitigate CVE-2023-29183, European organizations should immediately apply any available patches or updates from Fortinet once released, as this is the most effective remediation. Until patches are deployed, restrict access to the FortiProxy and FortiOS management interfaces to trusted administrators only, ideally through network segmentation and VPNs with strong authentication mechanisms. Implement multi-factor authentication (MFA) for all users accessing the management GUI to reduce the risk of credential compromise. Monitor logs and network traffic for unusual activity indicative of attempted exploitation or lateral movement. Educate administrators about the risks of social engineering and phishing attacks that could facilitate user interaction required for exploitation. Consider deploying web application firewalls (WAFs) or intrusion prevention systems (IPS) with signatures targeting Fortinet GUI vulnerabilities to detect and block malicious payloads. Regularly review and harden guest management settings and other configurable parameters to minimize exposure. Finally, maintain an incident response plan tailored to web interface compromises to enable rapid containment and recovery if exploitation occurs.