CVE-2025-59452 identifies a vulnerability in the YoSmart YoLink API where endpoint URLs are generated using a combination of a device's MAC address and an MD5 hash of a non-secret key starting with 'cf50'. The use of MAC addresses, which are globally unique but publicly accessible identifiers, combined with MD5 hashes of non-secret information, results in predictable endpoint URLs. This predictability violates secure design principles outlined in CWE-340, which warns against generating predictable numbers or identifiers. Because the API endpoints can be derived without authentication or user interaction, an attacker with network access can enumerate or guess valid endpoints, potentially gaining unauthorized insight into device presence or status. The vulnerability has a CVSS 3.1 base score of 5.8 (medium severity), reflecting its network attack vector, low attack complexity, no privileges required, no user interaction, and a confidentiality impact limited to partial information disclosure. There are no known exploits in the wild, and no patches have been published yet. The vulnerability affects all versions up to the disclosed date (2025-10-02). The core issue stems from weak cryptographic practices (MD5 hashing of non-secret data) and reliance on static hardware identifiers, which can be easily obtained or spoofed. This flaw could be leveraged in reconnaissance phases of attacks targeting IoT devices managed via the YoLink API, potentially facilitating further exploitation or privacy breaches.

For European organizations, especially those deploying YoSmart IoT devices or integrating with the YoLink API, this vulnerability poses a risk of unauthorized information disclosure. Attackers could remotely enumerate device endpoints, gaining insights into device presence, network topology, or operational status without authentication. This could facilitate targeted attacks on IoT infrastructure, privacy violations, or unauthorized surveillance. While the vulnerability does not directly impact device integrity or availability, the confidentiality breach could undermine trust in IoT deployments and expose sensitive operational data. Sectors with high IoT adoption such as manufacturing, smart homes, healthcare, and critical infrastructure in Europe could face increased risk. Additionally, organizations with regulatory obligations under GDPR must consider the implications of unauthorized data exposure. The lack of known exploits reduces immediate risk, but the ease of exploitation and public availability of MAC addresses make this a credible threat vector that could be leveraged in multi-stage attacks.

YoSmart should urgently update the YoLink API to replace predictable endpoint URL generation with cryptographically secure random identifiers or tokens that do not rely on static hardware identifiers or weak hashes like MD5. Until a patch is available, organizations should restrict network access to IoT management interfaces, employing network segmentation and firewall rules to limit exposure. Monitoring API traffic for unusual or repeated endpoint access attempts can help detect reconnaissance activity. Employing anomaly detection systems focused on IoT traffic patterns is recommended. Organizations should also review IoT device inventory and ensure firmware and software are up to date. Where possible, implement additional authentication layers or API gateways that validate requests before forwarding them to the YoLink API. Educating staff about IoT security best practices and maintaining an incident response plan for IoT-related breaches will further reduce risk.