CVE-2025-48965 is a medium-severity vulnerability affecting Mbed TLS versions prior to 3.6.4. The flaw arises from an incorrect behavior order in the function mbedtls_asn1_store_named_data, which can lead to a NULL pointer dereference. Specifically, the vulnerability occurs when the function processes ASN.1 named data structures where the val.p pointer is NULL but val.len is greater than zero. This inconsistent state can cause the software to dereference a NULL pointer, resulting in a denial-of-service (DoS) condition due to application crashes or unexpected termination. The vulnerability is classified under CWE-696, which relates to incorrect behavior order, indicating that the sequence of operations or checks in the code is flawed, leading to unsafe memory access. 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), scope changed (S:C), and impact limited to availability (A:L) without affecting confidentiality or integrity. No known exploits are reported in the wild as of the publication date, and no patches are linked yet, suggesting that remediation may still be pending or in progress. Mbed TLS is widely used as a lightweight, portable cryptographic library in embedded systems, IoT devices, and networked applications, making this vulnerability relevant for any system relying on this library for secure communications or cryptographic operations.

For European organizations, the primary impact of CVE-2025-48965 is the potential for denial-of-service conditions in systems utilizing vulnerable versions of Mbed TLS. This can disrupt critical services, especially in sectors relying on embedded devices and IoT infrastructure such as manufacturing, healthcare, smart city deployments, and telecommunications. Since the vulnerability does not compromise confidentiality or integrity, the risk of data breaches or unauthorized data manipulation is low. However, availability disruptions can lead to operational downtime, loss of productivity, and potential safety risks in industrial control systems or medical devices. The medium CVSS score reflects that exploitation requires high attack complexity, reducing the likelihood of widespread automated attacks but not eliminating targeted attacks by skilled adversaries. European organizations with extensive IoT deployments or embedded systems should be particularly vigilant, as these environments often have limited patching capabilities and longer device lifecycles, increasing exposure duration. Additionally, the scope change in the CVSS vector indicates that exploitation may affect components beyond the vulnerable library, potentially impacting dependent applications or services.

To mitigate CVE-2025-48965, European organizations should first identify all systems and applications using Mbed TLS versions prior to 3.6.4. Given the absence of a direct patch link, organizations should monitor vendor advisories for the official patch release and apply updates promptly once available. In the interim, applying runtime protections such as memory safety checks, address sanitizers, or deploying application-level watchdogs can help detect and recover from crashes caused by NULL pointer dereferences. Network-level mitigations include restricting exposure of vulnerable services to untrusted networks and implementing intrusion detection systems to monitor for anomalous traffic patterns that could trigger the vulnerability. For embedded and IoT devices where patching is challenging, consider network segmentation and strict access controls to limit attack surface. Additionally, developers maintaining custom integrations with Mbed TLS should review and audit ASN.1 data handling code paths to ensure proper validation of pointers and lengths before dereferencing. Incorporating fuzz testing focused on ASN.1 parsing can help uncover similar issues proactively. Finally, maintain an inventory of affected devices and establish incident response plans to quickly address potential denial-of-service incidents.