CVE-2026-119740 in A95X
Summary
by MITRE • 11/02/2026
Nexbox A95X TV boxes built on the Amlogic S905X platform contain an unauthenticated console exposed via an internal UART header on the PCB that allows physical attackers to obtain an interactive shell as uid 2000 (system) without any credentials. Attackers with physical access and a USB-to-TTL adapter can leverage this shell to reach the pppoe_wrapper vendor daemon, which contains an OS command injection vulnerability executed as root, resulting in full root-level compromise of the device.
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Analysis
by VulDB Data Team • 11/02/2026
The Nexbox A95X television box, utilizing the Amlogic S905X system-on-chip architecture, presents a critical security deficiency rooted in improper hardware design and insecure default configurations. The primary vulnerability is an unauthenticated console accessible via an internal Universal Asynchronous Receiver-Transmitter header located on the printed circuit board. This UART interface remains enabled by default during manufacturing and lacks any form of authentication mechanism or access control list. Consequently, individuals with physical proximity to the device can exploit this hardware-level exposure without needing prior network access or remote credentials. The presence of such an open console represents a severe violation of secure boot principles and embedded system hardening standards, as it effectively bypasses all software-based security controls by providing direct low-level interaction with the operating system kernel and user space processes.
An attacker possessing physical access to the device can connect a USB-to-TTL serial adapter to the exposed UART pins on the motherboard. Upon establishing this connection, the attacker gains immediate entry into an interactive shell running under the uid 2000 identity, which corresponds to the system privilege level in Android-based environments. While this initial foothold does not grant root privileges directly, it provides a stable and persistent platform for further exploitation within the local environment. The existence of this unauthenticated shell allows attackers to enumerate running processes, inspect file permissions, and identify vulnerable services that are accessible from the user space context established by the console access.
The subsequent phase of the attack chain involves leveraging an operating system command injection vulnerability present in the pppoe_wrapper vendor daemon. This specific service is responsible for managing Point-to-Point Protocol over Ethernet connections, a common requirement for internet connectivity on many smart TV devices. Due to insufficient input validation and improper sanitization of user-supplied data within this daemon, an attacker can inject arbitrary shell commands into its execution context. Crucially, the pppoe_wrapper process executes with root-level privileges. This privilege escalation vector allows the command injection payload to be executed by the most powerful account on the system, effectively bridging the gap between the initial low-privilege UART access and full administrative control over the device.
The operational impact of this vulnerability chain is severe, resulting in a complete compromise of the Nexbox A95X TV box. With root-level access, an attacker can install persistent malware, exfiltrate sensitive user data such as viewing habits or connected network credentials, modify system configurations to maintain persistence, and potentially use the compromised device as a pivot point for attacks against other devices on the local network. The combination of physical UART exposure and high-privilege command injection creates a scenario where security boundaries are entirely bypassed through simple hardware manipulation rather than complex remote exploitation techniques. This aligns with CWE identifiers such as CWE-284 Improper Access Control, which describes failures in restricting access to resources, and CWE-78 OS Command Injection, which highlights the failure to neutralize special elements within commands. Furthermore, from a threat modeling perspective using the MITRE ATT&CK framework, this scenario illustrates techniques related to Initial Access via Physical Interaction and Privilege Escalation through exploitation of local vulnerabilities.
Mitigation strategies for this vulnerability must address both hardware design flaws and software configuration issues. Manufacturers should disable or physically remove UART headers on production units unless absolutely necessary for debugging during the development phase, ensuring that debug interfaces are not exposed in final consumer products. If physical access to such ports is unavoidable due to regulatory requirements, strict authentication mechanisms must be implemented at the bootloader level to prevent unauthorized shell access. On the software side, developers must rigorously validate and sanitize all inputs passed to system commands within vendor daemons like pppoe_wrapper to eliminate command injection vectors. Additionally, implementing principle of least privilege by ensuring that critical network services do not run with root permissions can significantly reduce the impact of such vulnerabilities. Regular security audits focusing on embedded Linux configurations and adherence to secure coding standards are essential to prevent similar issues in future firmware releases.