CVE-2025-53951 is a path traversal vulnerability classified under CWE-22 found in the Outlookproxy plugin of Fortinet's FortiDLP Agent for Windows, affecting versions 10.3.1 through 11.5.1. The flaw arises from improper limitation of pathname access, allowing an authenticated attacker to send a specially crafted request to a local listening port. This crafted request can exploit the vulnerability to escalate privileges from a lower-privileged user to the LocalService account, which has more extensive system privileges than a standard user but less than SYSTEM. The vulnerability requires the attacker to have local access and valid authentication credentials on the affected system, but no user interaction is necessary. The CVSS v3.1 base score is 4.9, indicating a medium severity level, with attack vector local (AV:L), low attack complexity (AC:L), privileges required low (PR:L), no user interaction (UI:N), and impacts on confidentiality, integrity, and availability rated as low (C:L/I:L/A:L). There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability could be leveraged to gain unauthorized access to sensitive data or disrupt data loss prevention mechanisms by elevating privileges within the FortiDLP agent environment. FortiDLP is widely used in enterprise environments to monitor and prevent data exfiltration, making this vulnerability a concern for organizations relying on this product for compliance and security.

For European organizations, the impact of CVE-2025-53951 could be significant in environments where FortiDLP is deployed to protect sensitive data and enforce data loss prevention policies. Successful exploitation allows an authenticated local attacker to escalate privileges to LocalService, potentially bypassing security controls and accessing or modifying protected data. This could lead to unauthorized data disclosure, tampering with data loss prevention logs or configurations, and disruption of monitoring capabilities. Organizations in regulated industries such as finance, healthcare, and critical infrastructure could face compliance violations and reputational damage if sensitive data is compromised. The requirement for local authentication limits the attack surface but insider threats or compromised credentials could facilitate exploitation. Additionally, the vulnerability could be chained with other exploits to achieve higher privilege levels or persistence. The medium severity rating suggests moderate risk, but the strategic importance of data protection in European enterprises elevates the need for timely mitigation.

1. Restrict access to the local listening port used by the FortiDLP Outlookproxy plugin through firewall rules or local access controls to limit exposure to authorized users only. 2. Monitor local network traffic and logs for unusual or unauthorized requests to the FortiDLP agent's listening ports, enabling early detection of exploitation attempts. 3. Enforce strict authentication and credential management policies to reduce the risk of compromised accounts being used to exploit this vulnerability. 4. Apply vendor patches or updates as soon as they become available to address the path traversal flaw directly. 5. Conduct regular security audits and vulnerability assessments on systems running FortiDLP to identify and remediate potential weaknesses. 6. Implement endpoint protection solutions capable of detecting suspicious local activity or privilege escalation attempts. 7. Educate system administrators and security teams about this vulnerability and the importance of limiting local access to critical security agents. 8. Consider network segmentation to isolate systems running FortiDLP agents from less trusted user groups or devices.