CVE-2026-86148 in CP3
Summary
by MITRE • 09/06/2026
A security flaw has been discovered in Tenda CP3 27.5.57.101. This vulnerability affects the function SystemAsh of the file Apis/system.c of the component Kylin. The manipulation of the argument AlarmVoiceURL results in os command injection. It is possible to launch the attack remotely.
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Analysis
by VulDB Data Team • 09/06/2026
A critical remote code execution vulnerability has been identified within the Tenda CP3 device, specifically affecting firmware version 27.5.57.101. This flaw resides in the Kylin component and manifests through improper input validation in the SystemAsh function located in the Apis/system.c source file. The root cause of this security issue is a classic OS command injection vulnerability triggered by the manipulation of the AlarmVoiceURL argument. When an attacker provides maliciously crafted input for this parameter, the application fails to adequately sanitize or validate the data before passing it to underlying operating system commands. This lack of proper boundary enforcement allows arbitrary shell commands to be executed with the privileges of the compromised service, typically root or a high-privilege user account within the embedded Linux environment.
The operational impact of this vulnerability is severe due to its remote exploitability and the privileged context in which it operates. An unauthenticated attacker can leverage this flaw over the network to achieve full control over the affected device. By injecting specific shell metacharacters such as semicolons, pipes, or backticks into the AlarmVoiceURL field, an adversary can bypass intended application logic and execute arbitrary system commands. This capability effectively transforms a simple IoT endpoint into a pivot point for further network intrusion. The attacker may use this access to exfiltrate sensitive data stored on the device, install persistent malware such as botnet agents like Mirai variants, or disrupt local services by terminating critical processes. Given that many Tenda devices are deployed in residential and small business environments with limited security awareness, successful exploitation can lead to significant privacy breaches and contribute to large-scale distributed denial-of-service attacks when aggregated across multiple compromised units.
From a classification perspective, this vulnerability aligns directly with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The attack vector is categorized under ATT&CK technique T1059 Command and Scripting Interpreter, specifically leveraging shell commands to execute arbitrary code remotely. This reflects a fundamental failure in secure coding practices where user-supplied input is treated as executable code rather than data. Such flaws are prevalent in embedded systems development due to resource constraints and the frequent reuse of legacy codebases that lack modern security controls like parameterized queries or strict allow-listing for command arguments.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary solution is to apply the vendor-provided firmware update if available, which should include proper input sanitization in the SystemAsh function. Developers must implement rigorous validation routines that enforce an allow-list of permitted characters or values for the AlarmVoiceURL parameter, rejecting any input containing shell metacharacters such as ; | & $ ` \ and newlines. Additionally, employing a whitelist approach where only expected URL formats are accepted can significantly reduce the attack surface. For organizations unable to immediately patch their devices, network-level controls should be implemented to restrict access to the management interfaces of these IoT devices from untrusted networks. Deploying intrusion detection systems configured with signatures for common command injection payloads can also provide an additional layer of defense by alerting administrators to attempted exploitation activities before successful compromise occurs.