CVE-2025-54983 is a vulnerability classified under CWE-772 (Missing Release of Resource after Effective Lifetime) affecting the Zscaler Client Connector (ZCC) on Windows platforms, specifically versions 4.6 prior to 4.6.0.216 and 4.7 prior to 4.7.0.47. The issue arises from a health check port that is intended to be used temporarily for monitoring or diagnostic purposes. However, due to improper resource management, this port remains open or active beyond its intended lifetime under certain conditions. This lingering port state can be exploited to bypass the forwarding controls implemented by ZCC, which are designed to enforce network traffic policies and security filtering. The vulnerability requires local access with low privileges (AV:L, PR:L) but does not require user interaction (UI:N). The scope is classified as changed (S:C), meaning the vulnerability can affect resources beyond the initially compromised component. The impact includes partial loss of confidentiality and integrity (C:L, I:L) but no impact on availability (A:N). By circumventing forwarding controls, attackers could route traffic outside of the expected security perimeter, potentially exposing sensitive data or injecting unauthorized traffic. Although no exploits have been observed in the wild, the vulnerability presents a risk especially in environments relying heavily on Zscaler for secure network access. The absence of a patch link suggests that fixes may be forthcoming or in development. Organizations should monitor vendor advisories closely. The vulnerability highlights the importance of proper resource lifecycle management in security-critical software components.

For European organizations, the impact of CVE-2025-54983 can be significant, particularly for those relying on Zscaler Client Connector to enforce network security policies and protect sensitive data. The ability to bypass forwarding controls may allow attackers or malicious insiders to exfiltrate data, access unauthorized network segments, or evade detection by security monitoring tools. This undermines confidentiality and integrity protections, potentially leading to data breaches or compliance violations under regulations such as GDPR. Critical sectors like finance, healthcare, and government, which often use Zscaler solutions for secure remote access and cloud security, are at heightened risk. The requirement for local privileges limits remote exploitation but does not eliminate risk, as insider threats or compromised endpoints could leverage this flaw. The lack of availability impact means service disruption is unlikely, but stealthy data leakage or policy circumvention could persist undetected. Overall, the vulnerability could weaken the security posture of European enterprises relying on Zscaler for network traffic control and monitoring.

1. Monitor Zscaler’s official channels for the release of patches addressing CVE-2025-54983 and apply updates to ZCC versions 4.6 and 4.7 promptly once available. 2. Until patches are deployed, implement strict endpoint security controls to limit local user privileges and prevent unauthorized access to affected systems. 3. Conduct network traffic analysis to identify anomalous patterns that may indicate bypass of forwarding controls, focusing on unexpected open ports or unusual routing behavior. 4. Employ host-based intrusion detection systems (HIDS) to monitor for suspicious activity related to the health check port or ZCC processes. 5. Review and tighten internal network segmentation to reduce the impact of potential lateral movement if forwarding controls are bypassed. 6. Educate IT and security teams about this specific vulnerability to enhance detection and response capabilities. 7. Consider temporary compensating controls such as firewall rules restricting local port usage or disabling non-essential diagnostic features if feasible. 8. Maintain comprehensive logging and audit trails for network traffic and endpoint activities to facilitate forensic investigations if exploitation is suspected.