CVE-2019-6697 in FortiOS
Summary
by MITRE • 03/17/2025
An Improper Neutralization of Input vulnerability affecting FortiGate version 6.2.0 through 6.2.1, 6.0.0 through 6.0.6 in the hostname parameter of a DHCP packet under DHCP monitor page may allow an unauthenticated attacker in the same network as the FortiGate to perform a Stored Cross Site Scripting attack (XSS) by sending a crafted DHCP packet.
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Analysis
by VulDB Data Team • 07/25/2025
The vulnerability CVE-2019-6697 represents a critical security flaw in Fortinet FortiGate firewalls that affects versions 6.2.0 through 6.2.1 and 6.0.0 through 6.0.6. This issue manifests as an improper neutralization of input within the hostname parameter of DHCP packets processed through the DHCP monitor page functionality. The vulnerability operates under the Common Weakness Enumeration classification of CWE-79 which specifically addresses Cross-Site Scripting flaws, making it a significant concern for network security infrastructure. Attackers exploiting this vulnerability can leverage the stored XSS vector to inject malicious scripts into the FortiGate's web interface, potentially compromising the entire network monitoring and management system.
The technical exploitation of this vulnerability occurs when an unauthenticated attacker within the same network segment sends a specially crafted DHCP packet containing malicious input in the hostname parameter. The FortiGate device fails to properly sanitize or escape this input before displaying it in the DHCP monitor page, creating a persistent XSS vulnerability. When network administrators or users view the DHCP monitor page, the malicious script executes in their browser context, potentially allowing attackers to steal session cookies, perform unauthorized actions, or redirect users to malicious sites. This stored nature of the vulnerability means the malicious code persists until the affected FortiGate is rebooted or the specific DHCP entry is manually removed from the monitoring interface.
The operational impact of CVE-2019-6697 extends far beyond a simple web interface compromise, as FortiGate devices serve as critical network security appliances that monitor and control traffic flow. Network administrators who access the FortiGate web interface regularly become potential victims of this attack, creating a persistent threat vector that could remain undetected for extended periods. The vulnerability directly violates the principle of least privilege and input validation, as the device should never trust or display untrusted input without proper sanitization. Organizations using affected FortiGate versions face potential data breaches, unauthorized network access, and complete compromise of their network monitoring capabilities, which could go unnoticed for weeks or months depending on monitoring practices.
Organizations should immediately implement mitigation strategies including upgrading to Fortinet FortiOS versions 6.2.2, 6.0.7, or later, which contain the necessary patches for this vulnerability. Network segmentation and access controls should be enhanced to limit who can access the FortiGate web interface, while monitoring systems should be configured to detect unusual DHCP activity patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1059.001 (Command and Scripting Interpreter: PowerShell) and T1566.001 (Phishing: Spearphishing Attachment) as attackers may use the compromised interface to launch further attacks. Additionally, implementing web application firewalls and regular security assessments of network infrastructure can help detect and prevent exploitation attempts, while maintaining comprehensive audit logs of all DHCP activity and web interface access can aid in forensic analysis if compromise occurs.