CVE-2019-15706 in FortiProxy
Summary
by MITRE • 03/17/2025
An improper neutralization of input during web page generation in the SSL VPN portal of FortiProxy version 2.0.0, version 1.2.9 and below and FortiOS version 6.2.1 and below, version 6.0.8 and below, version 5.6.12 may allow a remote authenticated attacker to perform a stored cross site scripting attack (XSS).
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Analysis
by VulDB Data Team • 07/25/2025
The vulnerability identified as CVE-2019-15706 represents a critical security flaw in FortiProxy and FortiOS SSL VPN portal implementations that enables stored cross site scripting attacks through improper input sanitization during web page generation. This weakness affects multiple versions of FortiProxy including 2.0.0 and earlier releases, as well as various FortiOS versions up to 6.2.1 and below, 6.0.8 and below, and 5.6.12 and below, creating a widespread exposure across enterprise network security infrastructure. The vulnerability specifically targets the SSL VPN portal component where user input is processed and rendered in web pages without adequate sanitization mechanisms.
The technical flaw stems from insufficient validation and sanitization of user-supplied data within the web page generation process of the SSL VPN portal interface. When authenticated users interact with the portal, their input data is stored in the system and later retrieved for display in web pages without proper neutralization of potentially malicious content. This creates a persistent XSS vulnerability where an attacker can inject malicious scripts that execute in the context of other users' browsers when they view affected pages. The vulnerability operates at the application layer and leverages the trust relationship between the SSL VPN portal and authenticated users to deliver malicious payloads through legitimate system interfaces.
The operational impact of this vulnerability is significant as it allows remote authenticated attackers to execute arbitrary code in victims' browsers, potentially leading to session hijacking, credential theft, and privilege escalation within the network environment. Attackers can craft malicious input that gets stored in the system and subsequently executed when other users access the affected portal, making this a persistent threat that can compromise multiple users over time. The vulnerability affects the integrity and confidentiality of the SSL VPN service, potentially allowing unauthorized access to sensitive network resources and undermining the security posture of organizations relying on Fortinet's SSL VPN solutions.
Organizations should immediately apply the latest security patches provided by Fortinet to address this vulnerability, as the company has released firmware updates specifically targeting this issue. Network administrators should also implement additional monitoring and logging of SSL VPN portal activities to detect potential exploitation attempts. The vulnerability aligns with CWE-79, which describes improper neutralization of input during web page generation, and maps to ATT&CK technique T1059.001 for command and scripting interpreter. Security teams should conduct comprehensive vulnerability assessments of their Fortinet deployments and consider implementing web application firewalls to provide additional protection layers against such attacks. The affected systems should be prioritized for immediate remediation to prevent potential exploitation that could lead to unauthorized network access and data compromise.