CVE-2026-1682 is a vulnerability identified in the Free5GC Session Management Function (SMF) component, specifically in versions 4.0 and 4.1.0. The flaw resides in the HandlePfcpAssociationReleaseRequest function within the PFCP UDP Endpoint module (file internal/pfcp/handler/handler.go). This function improperly handles certain PFCP (Packet Forwarding Control Protocol) association release requests, leading to a null pointer dereference condition. When exploited, this causes the SMF process to crash, resulting in a denial of service (DoS) condition. The vulnerability can be triggered remotely by sending crafted PFCP messages over UDP, without requiring any authentication or user interaction, making exploitation relatively easy. The CVSS 4.0 base score is 6.9 (medium severity), reflecting the network attack vector, low attack complexity, no privileges or user interaction required, and impact limited primarily to availability. The SMF is a critical 5G core network function responsible for managing session contexts and policies, so its disruption can impact subscriber connectivity and service continuity. Although no active exploits have been observed in the wild, a public exploit has been published, increasing the likelihood of future attacks. No patches or mitigation links were provided in the source, but it is recommended to apply vendor updates once available. The vulnerability highlights the importance of robust input validation and error handling in protocol implementations within 5G core components.

For European organizations, particularly telecom operators and 5G service providers, this vulnerability poses a risk of service disruption due to denial of service attacks on the SMF component. The SMF manages session states and policies critical to subscriber connectivity; its failure can lead to dropped sessions, degraded network performance, and potential outages affecting end users and enterprise customers. This can impact revenue, customer trust, and regulatory compliance, especially under stringent EU telecom regulations. The remote and unauthenticated nature of the exploit increases the attack surface, potentially allowing attackers to disrupt services from outside the network perimeter. Given the growing deployment of 5G networks across Europe, including private 5G networks in industries, the vulnerability could affect a wide range of sectors relying on 5G connectivity. The absence of known active exploits currently limits immediate risk, but the public availability of exploit code necessitates urgent mitigation to prevent future attacks.

1. Apply official patches or updates from Free5GC as soon as they become available to address the null pointer dereference in the HandlePfcpAssociationReleaseRequest function. 2. Implement network-level filtering and anomaly detection to block or flag malformed PFCP association release requests, especially from untrusted sources. 3. Employ rate limiting on PFCP traffic to reduce the risk of DoS attacks targeting the SMF. 4. Conduct thorough code audits and fuzz testing on PFCP handling code to identify and remediate similar vulnerabilities proactively. 5. Deploy redundancy and failover mechanisms for the SMF to maintain session management continuity in case of crashes. 6. Monitor SMF logs and network traffic for unusual PFCP message patterns indicative of exploitation attempts. 7. Restrict PFCP UDP endpoint exposure to trusted network segments and use secure network segmentation to limit attacker access. 8. Engage with Free5GC community and vendors for timely security advisories and best practices related to 5G core components.