CVE-2025-59452 identifies a vulnerability in the YoSmart YoLink API related to the generation of predictable endpoint URLs. The API constructs these URLs using a device's MAC address combined with an MD5 hash of a non-secret key starting with 'cf50'. Since the MAC address is a fixed hardware identifier and MD5 hashing of non-secret information is reversible or guessable, attackers can predict or enumerate valid API endpoints. This predictability violates secure design principles outlined in CWE-340, which warns against generating predictable numbers or identifiers. The vulnerability allows unauthenticated remote attackers to infer device endpoints, potentially facilitating unauthorized information gathering or targeted attacks. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N) indicates the attack can be performed remotely over the network with low complexity, no privileges, and no user interaction, affecting confidentiality with a scope change. No integrity or availability impacts are noted. No patches or known exploits are currently reported, but the vulnerability remains exploitable until fixed. The YoLink API is used in IoT devices managed by YoSmart, which may include smart home or industrial IoT products. The use of MD5 and predictable inputs for endpoint generation is a cryptographic weakness that should be remediated by adopting secure random or cryptographically strong identifiers and avoiding exposure of hardware identifiers in URLs.

For European organizations, the primary impact is the potential exposure of device endpoint information, which can lead to reconnaissance by threat actors. This exposure could facilitate further targeted attacks, such as unauthorized access attempts, device fingerprinting, or privacy breaches. While the vulnerability does not directly allow device control or data modification, it lowers the barrier for attackers to identify and target specific IoT devices. Organizations relying on YoSmart's IoT infrastructure for smart building management, industrial automation, or consumer smart home devices may face increased risk of information leakage. This could result in reputational damage, regulatory scrutiny under GDPR if personal data is indirectly exposed, and increased operational risk. The medium severity reflects that while the vulnerability is exploitable remotely without authentication, the impact is limited to confidentiality and does not disrupt device functionality or integrity. However, given the growing reliance on IoT in European critical infrastructure and enterprises, even information disclosure vulnerabilities warrant prompt attention.

1. Restrict network access to YoLink API endpoints using network segmentation and firewall rules to limit exposure to trusted IP ranges. 2. Monitor API traffic for unusual enumeration patterns or repeated requests that may indicate exploitation attempts. 3. Engage with YoSmart to obtain timelines for patches or updates that replace predictable endpoint generation with cryptographically secure random identifiers. 4. Where possible, avoid exposing device MAC addresses or other hardware identifiers in URLs or API parameters. 5. Implement strong authentication and authorization controls around IoT device management interfaces to reduce risk from endpoint enumeration. 6. Conduct regular security assessments of IoT deployments to identify similar weaknesses in identifier generation. 7. Educate operational teams on the risks of predictable identifiers and the importance of applying vendor updates promptly once available.