CVE-2025-53951 is a path traversal vulnerability (CWE-22) identified in the Outlookproxy plugin of Fortinet's FortiDLP Agent on Windows platforms, affecting versions 10.3.1 through 11.5.1. The vulnerability arises from improper validation of pathname inputs, allowing an authenticated attacker with local access to send crafted requests to a local listening port and escalate their privileges to the LocalService account. This escalation can enable the attacker to perform actions with higher privileges than originally granted, potentially compromising system confidentiality, integrity, and availability. The attack vector requires local access and valid authentication, but no user interaction is needed, which lowers the barrier for exploitation once access is obtained. The CVSS v3.1 score is 4.9 (medium), reflecting the limited attack vector (local), low complexity, and partial impact on confidentiality, integrity, and availability. No public exploits have been reported yet, but the vulnerability is significant for environments relying on FortiDLP for data loss prevention, as privilege escalation could lead to bypassing security controls or further lateral movement within networks. Fortinet has published the vulnerability with a reserved date in July 2025 and a publication date in October 2025, but no patch links are currently provided, indicating that remediation may be pending or forthcoming.

For European organizations, the impact of CVE-2025-53951 can be substantial, especially for those in regulated industries such as finance, healthcare, and critical infrastructure where FortiDLP is deployed to prevent data exfiltration. Successful exploitation could allow attackers to escalate privileges locally, potentially bypassing data loss prevention controls and accessing sensitive information or disrupting operations. This could lead to data breaches, regulatory non-compliance, and reputational damage. The requirement for local authentication limits remote exploitation but insider threats or compromised credentials could be leveraged. Additionally, organizations with large Fortinet deployments or those integrating FortiDLP tightly into their security stack may face increased risk. The medium severity rating suggests that while the vulnerability is not critical, it should not be ignored, particularly in environments with high-value data or stringent compliance requirements.

1. Monitor Fortinet’s official channels for patches or updates addressing CVE-2025-53951 and apply them promptly once available. 2. Restrict local access to the FortiDLP Agent’s Outlookproxy plugin listening ports using host-based firewalls or network segmentation to limit exposure to authenticated users only. 3. Enforce strict access controls and multi-factor authentication for accounts with local access to systems running FortiDLP to reduce the risk of credential compromise. 4. Implement application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous local requests or privilege escalation attempts targeting FortiDLP components. 5. Conduct regular audits of local user privileges and remove unnecessary local accounts or privileges to minimize the attack surface. 6. Educate system administrators and security teams about this vulnerability to increase awareness and readiness to respond to potential exploitation attempts. 7. Use network monitoring tools to detect unusual traffic patterns or crafted requests directed at local listening ports associated with FortiDLP.