Overview
A critical security vulnerability, identified as CVE-2025-46373, has been discovered in Fortinet FortiClientWindows. This vulnerability is a heap-based buffer overflow (CWE-122) that could allow a local, authenticated attacker to execute arbitrary code on a vulnerable system. This poses a significant risk to organizations utilizing affected versions of FortiClientWindows.
Technical Details
CVE-2025-46373 is a Heap-based Buffer Overflow vulnerability [CWE-122] affecting the following Fortinet FortiClientWindows versions:
- FortiClientWindows 7.4.0 through 7.4.3
- FortiClientWindows 7.2.0 through 7.2.8
The vulnerability resides within the “fortips_74.sys” driver. An authenticated local IPSec user can exploit this vulnerability to overwrite memory on the heap, potentially leading to arbitrary code execution. The attacker must successfully bypass Windows heap integrity protections to successfully exploit the vulnerability. Exploitation of this vulnerability could grant the attacker elevated privileges and control over the compromised system.
Simplified example of potential exploitation (Illustrative purpose only):
// Example (Conceptual - Not actual exploit code)
// Assumes attacker has local access and valid IPSec credentials
// and has bypassed heap protections
// Function triggering the overflow in fortips_74.sys
void trigger_overflow(char* input) {
// Vulnerable code inside fortips_74.sys
char buffer[256];
strcpy(buffer, input); // Heap-based buffer overflow if input > 256 bytes
}
int main() {
char malicious_input[512];
memset(malicious_input, 'A', 511); // Fill with overflow data
malicious_input[511] = '\0'; // Null terminate the string
trigger_overflow(malicious_input); //Trigger vulnerable function
return 0;
}
Disclaimer: The code above is for illustrative purposes only and may not be directly executable. Exploiting vulnerabilities without authorization is illegal and unethical.
CVSS Analysis
The vulnerability has been assigned a CVSS score of 7.8, indicating a high severity. The CVSS vector provides further details:
- CVSS Score: 7.8
- Severity: HIGH
- The specific CVSS vector string is not available at this moment from the information provided. It’s important to consult the official Fortinet advisory for the complete CVSS vector when it’s released. It typically includes information about Attack Vector, Attack Complexity, Privileges Required, User Interaction, Scope, Confidentiality Impact, Integrity Impact, and Availability Impact.
Possible Impact
Successful exploitation of CVE-2025-46373 can have severe consequences:
- Arbitrary Code Execution: An attacker can execute arbitrary code with the privileges of the FortiClientWindows service.
- Privilege Escalation: The attacker can potentially escalate their privileges to gain SYSTEM-level access.
- Data Breach: An attacker can steal sensitive data, including credentials and confidential information.
- System Compromise: The entire system can be compromised, leading to complete loss of control.
- Lateral Movement: A compromised system can be used as a pivot point to attack other systems on the network.
Mitigation and Patch Steps
Fortinet has released updates to address this vulnerability. It is crucial to upgrade to a patched version of FortiClientWindows as soon as possible. Follow these steps to mitigate the risk:
- Identify Affected Systems: Determine which systems are running vulnerable versions of FortiClientWindows (7.4.0 – 7.4.3 and 7.2.0 – 7.2.8).
- Apply the Patch: Upgrade FortiClientWindows to a patched version. Refer to the Fortinet advisory (linked below) for specific version information.
- Monitor Systems: Monitor systems for any suspicious activity that may indicate exploitation attempts.
- Restrict Access: Limit local access to systems running FortiClientWindows.
- Enable Enhanced Security Features: Ensure that all available security features in FortiClientWindows are enabled, such as real-time protection and intrusion detection.
