CVE-2026-51934 in A18
Summary
by MITRE • 09/01/2026
Buffer Overflow vulnerability in Shenzhen Jixiang Tengda Technology Co., Ltd. Tenda A18 v.15.13.07.09 allows a remote attacker to execute arbitrary code via the fromSetCmdlineRun function
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Analysis
by VulDB Data Team • 09/01/2026
The identified security flaw represents a critical buffer overflow vulnerability located within the firmware of the Shenzhen Jixiang Tengda Technology Co., Ltd. Tenda A18 wireless router, specifically in version 15.13.07.09. This type of vulnerability arises when a program writes more data to a fixed-length block of memory than it can hold, causing adjacent memory locations to be overwritten with the excess data. In this specific instance, the flaw is situated within the fromSetCmdlineRun function, which appears to handle command-line input or configuration parameters without performing adequate bounds checking on user-supplied arguments. The lack of proper validation allows an attacker to supply a string that exceeds the allocated buffer size, leading to memory corruption and potentially altering the control flow of the application.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-120, which describes Buffer Overflow without description of write location, or more specifically CWE-121 if stack-based overflow is confirmed by reverse engineering efforts. The absence of boundary checks in the fromSetCmdlineRun function suggests a fundamental oversight in secure coding practices during the development phase. When an attacker crafts a malicious payload designed to exploit this buffer overflow, they can overwrite critical memory structures such as return addresses or function pointers on the stack. This manipulation enables the execution of arbitrary machine code injected by the attacker, effectively granting them full control over the affected device's processor state and instruction pointer.
The operational impact of successfully exploiting this vulnerability is severe, resulting in Remote Code Execution (RCE) with potentially elevated privileges depending on the context in which the vulnerable function operates. If the router processes these requests as part of a privileged service or daemon running with root-level access, an attacker can gain complete administrative control over the device. This compromise allows for unauthorized configuration changes, interception of network traffic through man-in-the-middle attacks, and the use of the compromised router as a pivot point to attack other devices on the local network. Furthermore, persistent backdoors may be installed, turning the IoT device into part of a botnet used for distributed denial-of-service (DDoS) attacks or cryptomining operations.
This exploitation scenario maps directly to several techniques within the MITRE ATT&CK framework, particularly T1059 Command and Scripting Interpreter if shell commands are executed via RCE, and T1136 Creation of Account for lateral movement if new administrative accounts are created post-exploitation. The ability to execute arbitrary code remotely places this vulnerability in a high-severity category according to standard scoring systems like CVSS, given its potential for widespread impact across home and small business networks where such routers are commonly deployed without additional security layers.
Mitigation strategies must prioritize immediate firmware updates provided by the manufacturer if available, as patching typically involves adding strict input validation and length checks within the fromSetCmdlineRun function to prevent buffer overflows. In cases where patches are unavailable or delayed, network segmentation should be implemented to isolate IoT devices from critical internal assets. Additionally, disabling remote management features on the router can reduce the attack surface by preventing external actors from reaching the vulnerable service. Security monitoring tools should also be configured to detect anomalous traffic patterns indicative of exploitation attempts, such as unusually large POST requests or malformed HTTP headers targeting known vulnerable endpoints.