CVE-2025-65566 is a denial-of-service vulnerability affecting the User Plane Function (UPF) component pfcpiface of the omec-project, specifically version upf-epc-pfcpiface:2.1.3-dev. The vulnerability arises when the UPF receives a PFCP Session Report Response message that lacks the mandatory Cause Information Element. Instead of properly rejecting this malformed message, the session report handler attempts to dereference a nil pointer, triggering a runtime panic that terminates the UPF process. This results in a crash of the UPF, which is a critical network function responsible for forwarding user data in mobile networks. The attack vector requires an attacker to send crafted PFCP Session Report Response messages to the UPF's N4/PFCP endpoint, which is typically exposed internally within the mobile core network. No privileges or user interaction are required to exploit this vulnerability, making it remotely exploitable with low complexity. The impact is a disruption of user-plane services, causing denial of service to mobile subscribers relying on the affected UPF instance. The vulnerability is classified under CWE-476 (NULL Pointer Dereference), indicating a failure to validate input leading to unsafe memory access. The CVSS v3.1 base score is 7.5 (High), with metrics indicating network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact. No patches or known exploits are currently documented, but the vulnerability poses a significant risk to mobile network availability if exploited.

For European organizations, particularly telecom operators and mobile network providers deploying the omec-project UPF component, this vulnerability poses a significant risk to network availability. Exploitation can cause repeated crashes of the UPF, disrupting user-plane data forwarding and resulting in service outages for mobile subscribers. This can lead to degraded customer experience, potential regulatory scrutiny, and financial losses due to downtime. The disruption of user-plane services can affect critical communications, including emergency services and enterprise mobile applications. Additionally, the vulnerability could be leveraged as part of a broader attack to degrade network infrastructure resilience. Given the increasing reliance on 5G networks and the adoption of open-source components like omec-project in Europe, the impact could be widespread if not mitigated promptly. The lack of confidentiality or integrity impact limits data breach risks, but availability degradation in telecom infrastructure is critical and can have cascading effects on dependent services.

To mitigate CVE-2025-65566, European telecom operators should prioritize the following actions: 1) Apply vendor patches or updates as soon as they become available for the omec-project UPF pfcpiface component to ensure proper validation of PFCP messages. 2) Implement strict input validation and sanity checks on PFCP Session Report Response messages at the N4/PFCP interface to reject malformed or incomplete messages before processing. 3) Employ network segmentation and access controls to restrict which entities can send PFCP messages to the UPF, limiting exposure to untrusted sources. 4) Monitor UPF process stability and logs for signs of crashes or malformed PFCP messages to detect potential exploitation attempts early. 5) Consider deploying redundancy and failover mechanisms for UPF instances to maintain user-plane service continuity in case of crashes. 6) Collaborate with omec-project maintainers and the broader telecom security community to stay informed about patches and best practices. These targeted mitigations go beyond generic advice by focusing on protocol-level validation, network controls, and operational monitoring specific to the omec-project UPF environment.