CVE-2025-48965 is a vulnerability identified in the Mbed TLS cryptographic library, specifically affecting versions prior to 3.6.4. The root cause is an incorrect behavior order in the function mbedtls_asn1_store_named_data, which handles ASN.1 named data storage. This function can encounter a scenario where the pointer val.p is NULL while val.len is greater than zero, leading to a NULL pointer dereference. This dereference causes the application using the library to crash, resulting in a denial of service (DoS) condition. The vulnerability is classified under CWE-696, which relates to incorrect behavior order, indicating a logic flaw in the sequence of operations within the function. The CVSS v3.1 base score is 4.0, reflecting a medium severity level, with the vector indicating network attack vector (AV:N), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), and a scope change (S:C). The impact is limited to availability (A:L) with no confidentiality (C:N) or integrity (I:N) loss. There are no known exploits in the wild, and no official patches have been linked at the time of publication. The vulnerability primarily affects embedded systems and IoT devices that rely on Mbed TLS for secure communications, potentially causing service interruptions if exploited.

For European organizations, the primary impact of CVE-2025-48965 is the potential for denial of service in systems using vulnerable versions of Mbed TLS. This is particularly relevant for industries relying on embedded devices, IoT infrastructure, and secure communications where Mbed TLS is integrated. Disruptions could affect critical services, industrial control systems, and networked devices, leading to operational downtime and potential safety risks. Although the vulnerability does not compromise confidentiality or integrity, availability impacts can cause cascading effects in tightly coupled systems. Organizations in sectors such as manufacturing, automotive, healthcare, and telecommunications may face increased risk due to their reliance on embedded cryptographic libraries. The medium severity rating suggests that while exploitation is not trivial, the consequences of successful exploitation warrant proactive mitigation to maintain service continuity.

European organizations should implement the following specific mitigation steps: 1) Inventory all systems and devices using Mbed TLS to identify those running versions prior to 3.6.4. 2) Monitor official Mbed TLS channels and security advisories for the release of patches addressing CVE-2025-48965 and apply updates promptly. 3) Where immediate patching is not feasible, implement network-level protections such as intrusion detection/prevention systems (IDS/IPS) to monitor and block anomalous traffic targeting vulnerable services. 4) Employ robust input validation and error handling in applications interfacing with Mbed TLS to reduce the risk of triggering the NULL pointer dereference. 5) Conduct thorough testing of embedded and IoT devices to ensure stability and resilience against malformed ASN.1 data inputs. 6) Engage with device vendors to confirm patch availability and deployment timelines. 7) Consider network segmentation to isolate vulnerable devices and limit exposure. These measures go beyond generic advice by focusing on embedded device management, vendor coordination, and network controls tailored to the nature of this vulnerability.