CVE-2026-51380 in AC10
Summary
by MITRE • 07/16/2026
Buffer Overflow vulnerability in Tenda AC10 v3 (firmware V03.03.16.09) allows attackers to cause a permanent Denial of Service (DoS) or potentially execute remote code via the /cgi-bin/UploadCfg endpoint
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Analysis
by VulDB Data Team • 07/16/2026
This buffer overflow vulnerability exists within the Tenda AC10 v3 wireless router firmware version V03.03.16.09, specifically targeting the /cgi-bin/UploadCfg web endpoint that handles configuration file uploads. The flaw arises from insufficient input validation and bounds checking when processing user-supplied data through the upload interface, creating a classic stack-based buffer overflow condition that can be exploited by remote attackers. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, which represents a fundamental weakness in memory management where more data is written to a buffer than it can accommodate, leading to memory corruption and potential arbitrary code execution. When an attacker sends a malformed payload to the UploadCfg endpoint, the application fails to properly validate the size of incoming data before copying it into fixed-size buffers, allowing the overflow to overwrite adjacent memory locations including return addresses and control data structures.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution on the affected device, making it a critical security concern for network infrastructure. An attacker who successfully exploits this vulnerability could gain persistent access to the router's operating system, allowing them to modify network configurations, intercept traffic, establish backdoors, or use the compromised device as a pivot point for attacking other systems within the local network. The DoS aspect of the vulnerability means that even unsuccessful exploitation attempts could render the device permanently inoperable by corrupting critical system memory or crashing the web server process. This type of vulnerability aligns with ATT&CK technique T1210 which describes exploiting weaknesses in remote services, particularly those involving web-based administrative interfaces that are commonly accessible from external networks. The attack surface is particularly concerning given that many users leave their router administration interfaces exposed to the internet without proper access controls or network segmentation.
Mitigation strategies for this vulnerability should include immediate firmware updates from Tenda, which would contain patches addressing the buffer overflow conditions through proper input validation and bounds checking mechanisms. Network administrators should implement strict access control measures by restricting administrative interface access to trusted internal networks only, utilizing firewall rules to block external access to port 80 and 443 on router devices. The principle of least privilege should be applied by disabling unnecessary services and features, particularly web-based administration interfaces that are not required for normal operation. Additionally, network monitoring systems should be configured to detect anomalous traffic patterns associated with exploitation attempts, including large payload sizes being transmitted to upload endpoints. Organizations should also consider implementing network segmentation strategies that isolate critical infrastructure from general network access, reducing the potential impact of successful exploitation. Regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in other network devices, as this type of buffer overflow vulnerability is commonly found in embedded systems and network appliances due to resource constraints and legacy code implementation practices. The vulnerability demonstrates the importance of secure coding practices and thorough input validation in firmware development, particularly for devices that are permanently exposed to untrusted networks.