CVE-2026-86149 in CP3
Summary
by MITRE • 09/06/2026
A weakness has been identified in Tenda CP3 27.5.57.101. This issue affects some unknown processing of the file Net/NetCheckPing.cpp. This manipulation of the argument interface_name/host causes os command injection. The attack can be initiated remotely.
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Analysis
by VulDB Data Team • 09/06/2026
The vulnerability identified in Tenda CP3 firmware version 27.5.57.101 represents a critical security flaw rooted in improper input validation within the network diagnostic subsystem. Specifically, the defect resides in the file Net/NetCheckPing.cpp, which is responsible for handling ping operations to verify network connectivity. The core technical issue involves the manipulation of the interface_name or host argument passed by the application logic to underlying system commands. Instead of strictly validating and sanitizing these inputs against a whitelist of allowed characters or formats, the software directly incorporates them into operating system command strings without adequate escaping or restriction. This failure allows an attacker to inject arbitrary shell metacharacters, such as semicolons, pipes, or ampersands, effectively breaking out of the intended ping context and executing unintended commands on the host device.
This specific flaw is classified under Common Weakness Enumeration (CWE) ID 78, known as Improper Neutralization of Special Elements used in an OS Command, commonly referred to as OS command injection. The vulnerability arises because the application treats user-supplied or network-derived input as executable code rather than data. By failing to enforce strict type checking and character filtering on the host parameter before passing it to system-level functions like popen() or exec(), the firmware creates a direct pathway for remote exploitation. An attacker can craft maliciously formatted requests that, when processed by the vulnerable module, result in the execution of arbitrary commands with the privileges of the service running the ping functionality, which is often root level on embedded devices.
The operational impact of this vulnerability is severe due to its potential for remote initiation without authentication. Since network diagnostic tools are frequently exposed via web interfaces or API endpoints accessible from local networks, an attacker positioned within the same subnet can exploit this flaw to gain full control over the router. This compromise enables a wide range of malicious activities including data exfiltration, installation of persistent backdoors, pivoting into internal corporate networks, and disruption of network services through denial-of-service attacks or traffic redirection. The ability to execute commands remotely transforms a simple connectivity check feature into a powerful attack vector that undermines the integrity and confidentiality of the entire local area network protected by the device.
From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059, Command and Scripting Interpreter, specifically sub-techniques involving shell execution such as sh or bash on Linux-based embedded systems. Attackers can leverage this injection to download additional malware, modify firewall rules, or harvest sensitive information stored in configuration files accessible by the compromised process. The lack of input sanitization means that even minor updates or misconfigurations could inadvertently expose this vector if not properly addressed during development and testing phases.
Mitigation strategies must focus on immediate remediation through firmware updates provided by Tenda that address the input validation logic within NetCheckPing.cpp. Until an official patch is available, network administrators should restrict access to the router's management interface using strict firewall rules, limiting exposure only to trusted IP addresses. Additionally, implementing network segmentation can limit lateral movement if the device is compromised. Developers and security teams reviewing similar embedded firmware should enforce rigorous input validation practices, ensuring that all external inputs are validated against a whitelist of expected values before being passed to any system-level command execution functions. This approach eliminates the possibility of special character injection by rejecting any input that does not strictly conform to predefined safe patterns for hostnames or IP addresses.