CVE-2026-3802 in Tenda
Summary
by MITRE • 03/09/2026
A vulnerability was determined in Tenda i3 1.0.0.6(2204). Affected by this issue is the function formexeCommand of the file /goform/exeCommand. Executing a manipulation of the argument cmdinput can lead to stack-based buffer overflow. The attack may be performed from remote. The exploit has been publicly disclosed and may be utilized.
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Analysis
by VulDB Data Team • 03/09/2026
The vulnerability identified as CVE-2026-3802 affects the Tenda i3 router firmware version 1.0.0.6(2204) and represents a critical stack-based buffer overflow condition within the device's web interface. This flaw exists in the formexeCommand function located in the /goform/exeCommand file, which serves as an interface for executing system commands through the router's web management portal. The vulnerability stems from insufficient input validation and bounds checking when processing the cmdinput argument, creating an exploitable condition that allows remote attackers to manipulate the device's command execution functionality.
The technical implementation of this vulnerability involves a classic stack-based buffer overflow where malicious input exceeding the allocated buffer space in the cmdinput parameter can overwrite adjacent memory locations on the stack. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a high-severity issue in the Common Weakness Enumeration catalog. The attack vector is particularly concerning as it enables remote code execution without requiring authentication, making the vulnerability accessible to any attacker with network access to the device. The exploitation process typically involves crafting a specially formatted payload that overflows the buffer and potentially overwrites the return address on the stack, allowing an attacker to redirect execution flow and execute arbitrary code.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise of affected Tenda i3 devices. Attackers can leverage this vulnerability to gain unauthorized access to the router's operating system, potentially enabling them to modify network configurations, install malicious software, or establish persistent backdoors. The implications are particularly severe in network environments where these devices serve as primary gateways, as successful exploitation could provide attackers with access to the entire internal network. This vulnerability directly aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: PowerShell, though the actual exploitation would likely occur through direct shell command injection rather than PowerShell specifically. The public disclosure of exploitation methods significantly increases the risk to affected devices, as security researchers and malicious actors alike can readily implement the attack.
Mitigation strategies for CVE-2026-3802 should prioritize immediate firmware updates from Tenda, as the vendor is expected to release patches addressing the buffer overflow condition in the formexeCommand function. Network administrators should implement network segmentation to limit access to affected devices and consider disabling unnecessary web management interfaces when possible. Additional protective measures include deploying intrusion detection systems to monitor for exploitation attempts and implementing network access controls that restrict remote access to the affected device's management interfaces. Organizations should also conduct thorough vulnerability assessments to identify all instances of the affected firmware version and ensure that default credentials are changed immediately upon device deployment. The vulnerability's classification as a remote code execution flaw necessitates immediate action, as the combination of public exploit availability and the device's typical network exposure makes it a high-priority target for attackers. Security teams should also consider implementing continuous monitoring for unusual command execution patterns that might indicate exploitation attempts.