CVE-2026-129100 in TR3000
Summary
by MITRE • 11/13/2026
Cudy TR3000 before 2.5.42 contains a remote code execution vulnerability that allows authenticated administrators to execute commands as root by uploading crafted OpenVPN private or tls-auth keys. Attackers can close the inline key block with </key>, inject directives such as tls-verify that bypass the .ovpn denylist, and have OpenVPN execute the hook as root.
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Analysis
by VulDB Data Team • 11/13/2026
The vulnerability identified in Cudy TR3000 firmware versions prior to 2.5.42 represents a critical remote code execution flaw within the device's web-based management interface. This specific weakness stems from improper input validation and sanitization mechanisms when processing OpenVPN configuration files uploaded by authenticated administrators. While the system implements certain security controls, such as a denylist for prohibited directives in .ovpn configurations, these safeguards are insufficient against crafted inputs that exploit parsing ambiguities or logic errors in how the firmware processes key blocks and associated verification scripts. The core technical flaw lies in the handling of OpenVPN private keys and tls-auth parameters during the upload process. An attacker with valid administrative credentials can manipulate the structure of an uploaded configuration file to bypass existing restrictions, effectively turning a standard network management function into a vector for arbitrary command execution on the underlying operating system.
The exploitation mechanism relies on the specific syntax rules of the OpenVPN client software embedded within or managed by the router firmware. By uploading a crafted private key or tls-auth key file that contains an inline key block terminated with the closing tag </key>, the attacker can inject additional directives immediately following this closure. Specifically, injecting a directive such as tls-verify allows for the specification of an external script to be executed during the TLS handshake process. Because OpenVPN typically runs with elevated privileges to manage network interfaces and routing tables, any hook or verification script specified in these configurations is often executed with root-level permissions on the host system. This architectural design choice, common in many embedded networking devices that prioritize ease of configuration over strict privilege separation, creates a direct path from user-supplied input to high-privilege code execution without requiring further exploitation steps like buffer overflow techniques or race conditions.
From an operational impact perspective, this vulnerability grants an authenticated attacker complete control over the affected router. Once root access is achieved through the OpenVPN hook execution, the adversary can install persistent backdoors, exfiltrate sensitive network traffic data, modify routing tables to facilitate man-in-the-middle attacks within the local network, or pivot into other devices connected to the same subnet. The presence of an authentication requirement means that this vulnerability cannot be exploited by unauthenticated remote attackers over the internet unless administrative credentials have been previously compromised through weak passwords, credential stuffing, or other lateral movement techniques. However, in environments where internal trust is assumed or where administrators use default or easily guessable credentials, the risk profile escalates significantly to near-critical levels for overall network security posture.
This vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection), as it involves injecting executable code via configuration parameters that are interpreted by a system component. Furthermore, in terms of tactical mapping within the MITRE ATT&CK framework, this exploit technique corresponds to T1505.003 Server Software Component: Web Shell or more broadly to T1059 Command and Scripting Interpreter if considering the execution context, but specifically relates to T1486 Data Encrypted for Impact in scenarios where ransomware is deployed post-exploitation, though primarily it serves as a persistence mechanism akin to T1505. The lack of strict allow-listing for directives and insufficient sanitization of multi-part form data or file uploads exemplifies common pitfalls in embedded device development where security testing may be less rigorous than in enterprise software applications.
To mitigate this vulnerability, administrators must immediately update the firmware on all Cudy TR3000 devices to version 2.5.42 or later, which addresses the input validation flaws regarding OpenVPN configuration parsing. In addition to patching, it is advisable to enforce strong, complex passwords for administrative accounts and restrict access to the management interface via IP whitelisting if possible. Network segmentation should be implemented to limit the blast radius in case of a compromise, ensuring that compromised routers cannot easily reach critical internal assets. Future development practices for embedded networking equipment should prioritize strict allow-listing of permitted OpenVPN directives rather than relying on denylists, which are inherently prone to bypass through novel injection techniques or edge-case parsing behaviors. Regular security audits and penetration testing focused on configuration upload endpoints can help identify similar weaknesses in other network infrastructure components before they are exploited in the wild.