CVE-2025-70516 in Fanvil
Summary
by MITRE • 10/07/2026
The websocket handler of Fanvil x7a firmware version 2.6.0.1182 does not enforce proper authentication restrictions against sessionless users. The lack of restrictions grants anyone the ability to view any device resources such as operational logs or perform diagnostic requests.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified in Fanvil X7A IP phone firmware version 2.6.0.1182 represents a critical failure in access control mechanisms within the device's websocket handler component. This flaw stems from an insufficient authentication enforcement strategy that fails to validate session tokens or credentials for incoming requests originating from unauthenticated users. In secure web application architectures, stateful operations and sensitive data retrieval typically require a valid, active session established through proper login procedures. However, in this specific implementation, the server-side logic processes websocket connections without verifying whether the client has undergone an authorized authentication process. This architectural oversight effectively bypasses standard security boundaries, allowing any network actor to interact with internal device functions as if they were a legitimate administrator or user who has successfully logged into the system.
From a technical perspective, this vulnerability is classified under CWE-287, which denotes Improper Authentication. The root cause lies in the websocket handler's failure to check for valid session identifiers before executing commands or serving data. By not enforcing these restrictions against sessionless users, the application treats anonymous connections with the same level of trust as authenticated ones. This design flaw allows attackers who are on the same network segment—or potentially remote if exposed—to establish a direct connection to the websocket endpoint and issue requests without providing any proof of identity. The lack of input validation regarding user state creates an open channel for unauthorized interaction, fundamentally undermining the confidentiality and integrity guarantees expected from enterprise-grade communication devices.
The operational impact of this vulnerability is severe due to the sensitivity of the data accessible through these unrestricted endpoints. Attackers can exploit this flaw to view operational logs that may contain sensitive information about network topology, user activity, or internal system states. Furthermore, the ability to perform diagnostic requests means an attacker can gather detailed technical insights into the device's configuration and health status. This level of access facilitates reconnaissance activities that are typically reserved for authorized personnel. The exposure of such data not only compromises privacy but also aids in further exploitation by revealing potential weaknesses in other connected systems or network configurations, thereby increasing the overall risk profile for organizations relying on these devices for voice communications.
This vulnerability aligns with several tactics within the MITRE ATT&CK framework, specifically those related to Discovery and Collection. The ability to view operational logs corresponds to techniques such as System Information Discovery (T1082) or Application Log Discovery (T1506), where adversaries gather information about the environment to plan subsequent attacks. Additionally, performing diagnostic requests can be categorized under Device Diagnostic Discovery (T1592), which involves probing a target for vulnerabilities and configuration errors. These actions enable an attacker to build a comprehensive profile of the victim's infrastructure without triggering typical security alerts associated with brute-force login attempts or credential stuffing, as no authentication is required at all.
To mitigate this vulnerability, immediate firmware updates provided by Fanvil should be applied if available, as vendors typically release patches that enforce proper session validation in websocket handlers. In environments where patching is not immediately feasible, network segmentation strategies can help limit exposure by restricting access to the management interfaces of IP phones from untrusted networks. Implementing strict firewall rules that only allow authenticated administrative traffic on specific ports and protocols reduces the attack surface significantly. Additionally, deploying intrusion detection systems configured to monitor for unusual websocket activity patterns or unauthorized diagnostic requests can provide early warning indicators of exploitation attempts. Regular security audits focusing on access control implementations in embedded web services are also recommended to identify similar misconfigurations across other connected devices within the enterprise network.