CVE-2025-58324 is a stored cross-site scripting (XSS) vulnerability identified in Fortinet's FortiSIEM product, affecting versions 6.2.0 through 7.2.2. The root cause is improper neutralization of input during web page generation, classified under CWE-79. An authenticated attacker with high privileges can craft malicious HTTP requests that inject persistent scripts into the FortiSIEM web interface. When other users or administrators access the affected pages, the malicious scripts execute in their browsers, potentially allowing the attacker to execute unauthorized code or commands within the context of the victim's session. This can lead to theft of session tokens, privilege escalation, or manipulation of the FortiSIEM environment, impacting confidentiality, integrity, and availability of security monitoring data. The vulnerability requires both authentication with elevated privileges and user interaction, which reduces the likelihood of widespread exploitation but does not eliminate risk. The CVSS v3.1 score of 6.1 reflects medium severity, with network attack vector, high attack complexity, and partial user interaction. No public exploits have been reported yet, but the vulnerability's presence in widely deployed versions of FortiSIEM makes it a significant concern for organizations relying on this platform for security event management and incident response.

For European organizations, exploitation of this vulnerability could compromise the integrity and confidentiality of security event data managed by FortiSIEM, potentially allowing attackers to manipulate alerts, hide malicious activity, or gain unauthorized access to sensitive operational information. This undermines the effectiveness of security monitoring and incident response, increasing the risk of undetected breaches. Availability could also be affected if attackers disrupt FortiSIEM functionality. Organizations in sectors such as finance, energy, telecommunications, and government—where FortiSIEM is commonly deployed—face heightened risk due to the critical nature of their security operations. The requirement for authenticated access with high privileges somewhat limits exposure but also highlights the importance of protecting administrative credentials. Failure to address this vulnerability could lead to regulatory compliance issues under GDPR and other European data protection laws if security monitoring is compromised.

1. Apply official patches or updates from Fortinet as soon as they become available to address the input neutralization flaw. 2. Restrict administrative and high-privilege access to FortiSIEM interfaces using network segmentation, VPNs, and multi-factor authentication to reduce the risk of credential compromise. 3. Conduct regular audits of user accounts and permissions to ensure least privilege principles are enforced. 4. Implement web application firewalls (WAF) with rules designed to detect and block XSS payloads targeting FortiSIEM. 5. Monitor FortiSIEM logs and network traffic for unusual activity indicative of attempted exploitation or unauthorized script execution. 6. Educate administrators on the risks of XSS and safe handling of web interfaces. 7. Consider deploying Content Security Policy (CSP) headers if configurable within FortiSIEM to mitigate impact of injected scripts. 8. Maintain an incident response plan that includes procedures for handling potential compromise of security monitoring tools.