CVE-2026-2139 in TX9
Summary
by MITRE • 02/08/2026
A vulnerability was determined in Tenda TX9 up to 22.03.02.10_multi. Affected by this vulnerability is the function sub_432580 of the file /goform/fast_setting_wifi_set. This manipulation of the argument ssid causes buffer overflow. The attack may be initiated remotely. The exploit has been publicly disclosed and may be utilized.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/09/2026
The vulnerability identified as CVE-2026-2139 affects the Tenda TX9 router firmware version 22.03.02.10_multi and represents a critical buffer overflow condition within the device's web interface management system. This flaw exists in the sub_432580 function located in the /goform/fast_setting_wifi_set file, which handles wireless network configuration parameters. The vulnerability specifically manifests when processing the ssid argument, which is used to configure the wireless network name or service set identifier. This function fails to properly validate or limit the length of input data, creating an exploitable condition that allows attackers to overwrite adjacent memory locations in the router's operating system.
The technical implementation of this buffer overflow vulnerability stems from improper input validation mechanisms within the firmware's web form processing logic. When an attacker sends a specially crafted request containing an excessively long ssid parameter to the /goform/fast_setting_wifi_set endpoint, the system attempts to store this data in a fixed-size buffer without adequate bounds checking. This classic programming error allows for memory corruption that can be leveraged to execute arbitrary code on the affected device. The vulnerability's remote exploitability means that attackers do not require physical access to the device, as the flaw exists within the web-based management interface that typically operates over HTTP or HTTPS protocols.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it creates potential pathways for complete system compromise. An attacker who successfully exploits this buffer overflow could gain unauthorized access to the router's administrative functions, potentially enabling them to modify network settings, redirect traffic, or establish persistent backdoors. The publicly disclosed exploit available for this vulnerability increases the risk significantly, as it removes the requirement for advanced exploitation techniques and allows even less sophisticated attackers to leverage the flaw. This type of vulnerability directly relates to CWE-121, which addresses stack-based buffer overflow conditions, and aligns with ATT&CK techniques involving privilege escalation and persistence mechanisms.
Mitigation strategies for CVE-2026-2139 should prioritize immediate firmware updates from Tenda, as the vendor has likely released patches addressing this specific buffer overflow condition. Network administrators should implement network segmentation to limit access to affected devices and consider disabling unnecessary web management interfaces when possible. Additional defensive measures include deploying intrusion detection systems to monitor for suspicious requests targeting the vulnerable endpoint and implementing web application firewalls to filter malformed input parameters. The vulnerability's classification as a remote code execution flaw necessitates urgent remediation, as it provides attackers with a straightforward path to compromise network infrastructure. Organizations should also conduct thorough vulnerability assessments to identify other potentially affected devices within their network environment and establish monitoring protocols to detect exploitation attempts against similar firmware vulnerabilities.