CVE-2025-53609 is a Relative Path Traversal vulnerability affecting multiple versions of Fortinet's FortiWeb web application firewall (WAF) product, specifically versions 7.6.0 through 7.6.4, 7.4.0 through 7.4.8, 7.2.0 through 7.2.11, and 7.0.2 through 7.0.11. This vulnerability allows an authenticated attacker to craft specific requests that exploit the path traversal flaw to read arbitrary files on the underlying operating system hosting the FortiWeb appliance. The vulnerability arises due to insufficient validation of user-supplied input in file path parameters, enabling traversal sequences (e.g., "../") to access files outside the intended directory scope. The attacker must have authenticated access to the FortiWeb management interface or API, which limits the attack surface to users with valid credentials or those who can bypass authentication. The vulnerability does not allow modification or deletion of files (no integrity or availability impact), but the confidentiality impact is high as sensitive system files, configuration files, or credential stores could be exposed. The CVSS v3.1 base score is 4.7 (medium severity), reflecting network attack vector with low attack complexity but requiring high privileges and no user interaction. Exploitation does not require user interaction but does require authentication. There are no known exploits in the wild at the time of publication, and no official patches or mitigation links were provided in the source data. This vulnerability is classified as CWE-23 (Relative Path Traversal).

For European organizations deploying FortiWeb appliances, this vulnerability poses a significant risk to the confidentiality of sensitive information. FortiWeb is commonly used to protect web applications by filtering and monitoring HTTP traffic, and it often holds critical configuration and security data. An attacker with valid credentials could leverage this flaw to access sensitive files such as private keys, configuration files containing credentials, or logs that may reveal further attack vectors. This could lead to subsequent attacks like lateral movement, privilege escalation, or data exfiltration. Given the medium CVSS score and the requirement for authentication, the risk is primarily internal or from compromised credentials. However, in environments where FortiWeb is exposed to multiple administrators or third-party vendors, the attack surface increases. The confidentiality breach could affect compliance with GDPR and other European data protection regulations, potentially resulting in legal and financial repercussions. The lack of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits after public disclosure.

European organizations should immediately audit and restrict access to FortiWeb management interfaces to trusted personnel only, enforcing strong authentication mechanisms such as multi-factor authentication (MFA). Network segmentation should be applied to isolate FortiWeb appliances from general user networks and limit access to management interfaces. Organizations should monitor logs for unusual access patterns or failed attempts that could indicate exploitation attempts. Until patches are released, applying virtual patching via web application firewall rules to block suspicious path traversal sequences may reduce risk. Regularly updating FortiWeb firmware to the latest versions once patches become available is critical. Additionally, organizations should review and harden file permissions on the underlying system to minimize sensitive file exposure. Conducting internal penetration testing focusing on authenticated access to FortiWeb can help identify exploitation attempts. Finally, organizations should prepare incident response plans specific to potential data disclosure incidents involving FortiWeb appliances.