CVE-2025-50518 is a critical use-after-free vulnerability identified in the libcoap library, specifically within the coap_delete_pdu_lkd function in the coap_pdu.c source file. Libcoap is an open-source implementation of the Constrained Application Protocol (CoAP), which is widely used in IoT (Internet of Things) devices and constrained environments for lightweight machine-to-machine communication. The vulnerability arises due to improper handling of memory after a Protocol Data Unit (PDU) object has been freed. When an application incorrectly uses libcoap, the function attempts to access or manipulate memory that has already been released, leading to memory corruption. This corruption can be exploited by an attacker to execute arbitrary code remotely without requiring any privileges or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The vulnerability is classified under CWE-416 (Use After Free), a common and dangerous memory safety issue. Although the supplier disputes the vulnerability, claiming it only manifests when libcoap is misused, the high CVSS score of 9.8 reflects the severe potential impact if exploited. No patches are currently linked, and no known exploits have been reported in the wild yet. Given libcoap's role in IoT and constrained devices, this vulnerability poses a significant risk to embedded systems and networked devices that rely on CoAP for communication, especially if the application layer does not enforce correct usage patterns.

For European organizations, the impact of CVE-2025-50518 could be substantial, particularly for industries and sectors heavily reliant on IoT deployments, such as manufacturing, smart cities, utilities, healthcare, and transportation. Exploitation could lead to full system compromise of affected devices, resulting in unauthorized control, data theft, disruption of critical services, or lateral movement within networks. Given the critical severity and remote exploitability without authentication, attackers could leverage this vulnerability to infiltrate networks through vulnerable IoT endpoints, potentially bypassing perimeter defenses. This risk is amplified in environments where IoT devices are integrated into operational technology (OT) systems or critical infrastructure. Additionally, the lack of user interaction requirement facilitates automated exploitation campaigns. The disputed nature of the vulnerability suggests that organizations must carefully audit their use of libcoap to confirm whether their implementations are vulnerable. Failure to do so could expose European organizations to significant confidentiality, integrity, and availability risks, potentially leading to regulatory repercussions under GDPR if personal data is compromised.

To mitigate CVE-2025-50518 effectively, European organizations should: 1) Conduct a thorough inventory of all IoT and embedded devices using libcoap to identify potentially vulnerable systems. 2) Review and audit application code that integrates libcoap to ensure correct usage patterns, specifically avoiding scenarios that lead to use-after-free conditions in coap_delete_pdu_lkd. 3) Engage with libcoap maintainers or vendors for patches or updated versions that address this vulnerability once available. 4) Implement network segmentation and strict access controls to isolate IoT devices from critical network segments, reducing the attack surface. 5) Deploy runtime protection mechanisms such as memory safety tools (e.g., AddressSanitizer) during development and testing phases to detect improper memory handling. 6) Monitor network traffic for anomalous CoAP messages that could indicate exploitation attempts. 7) Establish incident response plans tailored to IoT device compromise scenarios. These steps go beyond generic advice by emphasizing code audits for correct library usage, proactive device identification, and network-level containment strategies.