Fortinet FortiOS Path Traversal Vulnerability Analysis and Mitigation Guide (CVE-2022-41328)

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2022-41328) is an improper limitation of a pathname to a restricted directory ('path traversal', CWE-22) within the CLI engine of Fortinet FortiOS. The root cause lies in the insufficient validation of file paths supplied to certain CLI commands. This flaw allows an authenticated, privileged attacker to bypass directory restrictions and access the underlying Linux operating system's file system.

2. Exploitation Mechanics & Attack Scenario

To exploit this vulnerability, an attacker must first obtain administrative privileges on the FortiOS device (e.g., via credential stuffing, compromised accounts, or other vulnerabilities). Once CLI access is established, the attacker executes specific file-handling commands containing directory traversal sequences (such as '../') or absolute paths. This enables the attacker to read sensitive configuration files or overwrite critical system binaries and startup scripts, establishing persistent, unauthorized access that survives device reboots.

3. Infrastructure & Business Impact

As FortiOS devices typically serve as critical perimeter firewalls and VPN gateways, compromise of these systems poses an extreme risk to the entire corporate network. This vulnerability is actively exploited in the wild and is listed in the CISA KEV catalog. Successful exploitation allows threat actors to establish a persistent foothold, intercept network traffic, compromise VPN sessions, and facilitate lateral movement into the internal network.