CVE-2025-47917 is a high-severity use-after-free vulnerability (CWE-416) found in Mbed TLS, a widely used open-source cryptographic library designed for embedded systems and IoT devices. The vulnerability exists in versions of Mbed TLS prior to 3.6.4. Specifically, the function mbedtls_x509_string_to_names() incorrectly manages memory for its 'head' argument. Although the documentation describes 'head' as an output argument without indicating that it will be freed, the function internally calls mbedtls_asn1_free_named_data_list() on this pointer, which performs a deep free operation. This discrepancy leads to application code retaining pointers to memory that has already been freed, resulting in use-after-free or double-free conditions. The vulnerability notably affects sample programs such as x509/cert_write and x509/cert_req, particularly when the Subject Alternative Name (SAN) string contains multiple Distinguished Names (DNs). Exploiting this flaw could allow attackers to execute arbitrary code, cause application crashes, or corrupt memory, impacting confidentiality, integrity, and availability of affected systems. The CVSS v3.1 base score is 8.9, reflecting a network attack vector with high impact on integrity and availability, although requiring high attack complexity and no privileges or user interaction. No known exploits are currently reported in the wild, but the vulnerability poses a significant risk due to the widespread use of Mbed TLS in embedded and IoT environments.

For European organizations, the impact of CVE-2025-47917 can be substantial, especially for industries relying on embedded systems and IoT devices that utilize Mbed TLS for secure communications. Sectors such as manufacturing, automotive, healthcare, and critical infrastructure may be particularly vulnerable due to their dependence on embedded cryptographic libraries for device authentication and secure data transmission. Exploitation could lead to unauthorized code execution, data breaches, or denial of service, potentially disrupting operations and compromising sensitive information. Given the vulnerability affects cryptographic certificate handling, it could undermine trust in device identity verification and secure communications, leading to broader security implications. Organizations operating in regulated environments within Europe, such as those subject to GDPR or NIS Directive, may face compliance risks if this vulnerability is exploited. Additionally, the high attack complexity somewhat reduces immediate risk but does not eliminate the threat, especially from advanced persistent threat (APT) actors targeting critical European infrastructure or high-value enterprises.

To mitigate CVE-2025-47917, European organizations should: 1) Immediately update Mbed TLS to version 3.6.4 or later, where the vulnerability is patched. 2) Audit all embedded and IoT devices, as well as software components, to identify usage of vulnerable Mbed TLS versions, focusing on applications that handle X.509 certificates and SAN fields. 3) Review and test application code that calls mbedtls_x509_string_to_names() to ensure it does not rely on the outdated documented behavior and does not retain pointers to freed memory. 4) Implement runtime memory safety tools or sanitizers during development and testing to detect use-after-free conditions. 5) Employ network-level protections such as intrusion detection systems (IDS) to monitor for anomalous activity targeting embedded devices. 6) Coordinate with device manufacturers and vendors to obtain firmware updates or patches for embedded products using vulnerable Mbed TLS versions. 7) Establish incident response plans that include monitoring for exploitation attempts and rapid patch deployment. These steps go beyond generic advice by emphasizing code audits, runtime detection, and supply chain coordination specific to embedded cryptographic libraries.