CVE-2025-66315 identifies a configuration defect in the ZTE MF258K Pro product line, specifically in the version server component. The vulnerability arises from improper directory permission settings that grant write access to a directory that should be more restricted. This improper privilege management (CWE-269) allows an attacker with limited privileges to write files remotely, potentially enabling disruption of device operations or denial of service conditions. The vulnerability is remotely exploitable over the network (AV:N), requires low attack complexity (AC:L), and only limited privileges (PR:L) but no user interaction (UI:N). The scope remains unchanged (S:U), and the impact is limited to availability (A:L), with no confidentiality or integrity impact. The affected firmware versions are ZTE_MF258kPRO_PLAY_V1.0.0B03 and ZTE_MF258PRO_STD_V1.0.0B04. Although no public exploits are currently known, the vulnerability could be leveraged by attackers to disrupt services or cause device instability. The lack of patch links suggests that a fix may not yet be publicly available, emphasizing the need for interim mitigations. The vulnerability’s medium CVSS score of 4.3 reflects its limited impact but ease of exploitation given network access and low privileges. This issue is particularly relevant for organizations deploying these devices in network edge or telecom environments.

For European organizations, the primary impact of CVE-2025-66315 is on the availability of ZTE MF258K Pro devices, which may be used in telecom networks, IoT deployments, or enterprise connectivity solutions. Successful exploitation could lead to denial of service or operational disruptions, affecting network reliability and service continuity. While confidentiality and integrity are not directly compromised, availability issues can cascade into broader operational challenges, especially in critical infrastructure or service provider environments. The vulnerability could be exploited by internal threat actors or remote attackers with limited privileges, increasing the risk in multi-tenant or shared network environments. Disruptions could affect customer services, regulatory compliance, and operational costs. The absence of known exploits reduces immediate risk but does not eliminate the potential for future attacks, especially as the vulnerability becomes more widely known. Organizations relying on ZTE MF258K Pro devices should assess their exposure and implement compensating controls to minimize risk.

1. Restrict network access to the version server and management interfaces of the ZTE MF258K Pro devices using firewall rules or network segmentation to limit exposure to trusted hosts only. 2. Monitor device logs and file system changes for unauthorized write activities in the affected directories to detect potential exploitation attempts early. 3. Apply principle of least privilege by ensuring that user accounts and services interacting with the device have minimal permissions necessary. 4. Engage with ZTE support or vendors to obtain firmware updates or patches addressing this vulnerability as soon as they become available. 5. If patching is not immediately possible, consider deploying network intrusion detection/prevention systems (IDS/IPS) with signatures targeting anomalous write operations or suspicious traffic patterns related to the version server. 6. Conduct regular security audits and vulnerability assessments on deployed ZTE devices to identify and remediate configuration weaknesses. 7. Educate network administrators about this vulnerability and enforce strict change management policies to prevent unauthorized configuration changes.