An unauthenticated remote denial of service vulnerability in free5gc v4.0.1 poses a significant risk to service availability and network stability.

This vulnerability involves improper input validation within the buildFilter function located in processor/processor.go. The flaw allows an unauthenticated remote attacker to trigger a crash, resulting in a denial of service.

The ability for an unauthenticated attacker to remotely disrupt service availability presents a severe operational risk. Given the CVSS score of 7.5, this vulnerability is classified as high severity, as it can lead to critical network downtime and impact downstream services that rely on the free5gc core. Organizations should prioritize mitigation to maintain continuous service delivery.

Immediate Action: Since a specific patch version is not currently listed, administrators should restrict access to the affected service via network firewalls and monitor the upstream free5gc repository for official security updates.

Proactive Monitoring: Security teams should monitor system logs for frequent application restarts or unexpected service termination patterns that may indicate exploitation attempts.

Compensating Controls: Deploy a Web Application Firewall or an API gateway to inspect and filter traffic, blocking requests that contain anomalous or malformed input structures targeting the processor component.

Public Exploit Available: Unknown

The high severity of this vulnerability necessitates immediate attention to prevent potential service outages. Administrators should ensure that the affected free5gc instance is isolated from untrusted networks and verify that all incoming traffic is strictly validated until a vendor-supplied patch is made available.