CVE-2025-36631 is a high-severity vulnerability identified in Tenable Agent versions prior to 10.8.5 running on Windows hosts. The core issue stems from improper privilege management (CWE-269), where a non-administrative user can exploit the agent's logging mechanism to overwrite arbitrary local system files with log content executed at SYSTEM privilege level. This vulnerability allows an attacker with limited local privileges to escalate their rights significantly by modifying critical system files, potentially leading to system compromise. The vulnerability is characterized by a low attack vector (local access required), low attack complexity, and requires only low privileges without user interaction, but the scope is changed as the impact affects system-wide files. The CVSS v3.1 score is 8.4, reflecting high impact on integrity and availability, though confidentiality is not directly affected. The vulnerability does not require user interaction, making exploitation more straightforward once local access is obtained. No known exploits are reported in the wild as of the publication date (June 13, 2025), and no patches are currently linked, indicating that affected organizations should prioritize mitigation and monitoring. The vulnerability impacts the Tenable Agent, a widely used endpoint security and vulnerability management tool, which is often deployed in enterprise environments to monitor and secure assets. The flaw could be leveraged by malicious insiders or attackers who have gained limited access to escalate privileges and potentially disrupt system operations or implant persistent malicious code.

For European organizations, the impact of CVE-2025-36631 is significant due to the widespread use of Tenable Agent in enterprise security infrastructures. Successful exploitation can lead to unauthorized modification of critical system files, resulting in integrity breaches and potential denial of service or system instability. This could disrupt business operations, compromise compliance with data protection regulations such as GDPR, and increase the risk of further lateral movement within networks. Given that the vulnerability allows privilege escalation from a non-administrative user to SYSTEM level, attackers could gain full control over affected endpoints, undermining endpoint security and potentially facilitating ransomware deployment or data tampering. The lack of confidentiality impact reduces the risk of direct data leakage, but the high integrity and availability impact still pose severe operational and reputational risks. Organizations in sectors with stringent regulatory requirements (e.g., finance, healthcare, critical infrastructure) are particularly vulnerable to the operational disruptions and compliance violations that could arise from exploitation.

1. Immediate upgrade: Organizations should prioritize upgrading Tenable Agent to version 10.8.5 or later where this vulnerability is addressed. 2. Privilege restriction: Limit local user privileges strictly to reduce the number of users with local access to endpoints running the vulnerable agent. 3. File integrity monitoring: Implement monitoring solutions to detect unauthorized modifications to critical system files, especially those potentially targeted by log overwrites. 4. Application whitelisting: Employ application control policies to prevent unauthorized execution or modification of system files by non-administrative users. 5. Endpoint detection and response (EDR): Enhance endpoint monitoring to detect suspicious activities indicative of privilege escalation attempts. 6. Network segmentation: Restrict lateral movement by segmenting networks so that compromised endpoints have limited access to critical systems. 7. Incident response readiness: Prepare playbooks for rapid containment and remediation if exploitation is detected. 8. Audit and review: Regularly audit local user accounts and permissions to ensure minimal privilege principles are enforced. 9. Vendor communication: Monitor Tenable’s advisories for official patches or workarounds and apply them promptly once available.