CVE-2026-2180: Tenda RX3 Buffer Overflow Vulnerability

CVE-2026-2180 Overview

A stack-based buffer overflow vulnerability has been identified in Tenda RX3 router firmware version 16.03.13.11. The vulnerability exists in the /goform/fast_setting_wifi_set endpoint, where improper handling of the ssid_5g parameter allows an attacker to overflow the stack buffer. This firmware vulnerability can be exploited remotely by authenticated users, potentially leading to arbitrary code execution on the affected device.

Critical Impact

Remote attackers with low-level authentication can exploit this buffer overflow to gain complete control over the Tenda RX3 router, potentially compromising the entire network infrastructure.

Affected Products

• Tenda RX3 Firmware version 16.03.13.11
• Tenda RX3 hardware devices running vulnerable firmware
• Network environments utilizing affected Tenda RX3 routers

Discovery Timeline

• 2026-02-08 - CVE-2026-2180 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2026-2180

Vulnerability Analysis

This vulnerability is classified as a memory corruption issue (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The affected function within the /goform/fast_setting_wifi_set handler fails to properly validate the length of user-supplied input to the ssid_5g parameter before copying it into a fixed-size stack buffer.

When an attacker supplies an oversized string to the ssid_5g parameter, the data exceeds the allocated buffer boundaries on the stack, overwriting adjacent memory including potentially the return address. This classic stack-based buffer overflow pattern enables attackers to redirect program execution to attacker-controlled code.

The vulnerability is remotely exploitable over the network and requires only low-level privileges to trigger. No user interaction is required, making this an attractive target for automated exploitation. The exploit for this vulnerability has been publicly disclosed, increasing the urgency for remediation.

Root Cause

The root cause of CVE-2026-2180 is insufficient bounds checking in the WiFi configuration functionality. The firmware uses an unsafe string copy operation that does not verify whether the input length exceeds the destination buffer's capacity. This is a common vulnerability pattern in embedded device firmware where resource constraints sometimes lead to the omission of proper input validation.

Attack Vector

The attack is conducted remotely over the network against the router's web management interface. An authenticated attacker can craft a malicious HTTP POST request to the /goform/fast_setting_wifi_set endpoint with an oversized ssid_5g parameter value. The exploitation process involves:

1. Authenticating to the router's web interface (low privilege requirement)
2. Sending a crafted POST request to the vulnerable endpoint
3. Including a specially crafted payload in the ssid_5g parameter
4. The overflow corrupts stack memory, enabling code execution

Technical details and proof-of-concept information can be found in the GitHub Issue Discussion and the VulDB entry #344883.

Detection Methods for CVE-2026-2180

Indicators of Compromise

• Unusual HTTP POST requests to /goform/fast_setting_wifi_set with abnormally long ssid_5g parameter values
• Router crashes, reboots, or unexpected behavior following web interface interactions
• Unauthorized configuration changes or persistence mechanisms on the router
• Anomalous network traffic originating from the router to external IP addresses

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests with oversized parameters targeting Tenda router endpoints
• Monitor router logs for repeated access attempts to /goform/fast_setting_wifi_set from unexpected sources
• Implement web application firewall (WAF) rules to inspect and block requests with parameter lengths exceeding normal thresholds
• Use SentinelOne Singularity to detect post-exploitation activity and lateral movement originating from compromised network devices

Monitoring Recommendations

• Enable verbose logging on network perimeter devices to capture all traffic to and from Tenda routers
• Establish baseline network behavior for router management interfaces and alert on deviations
• Regularly audit router configurations for unauthorized changes
• Monitor for firmware modifications or unauthorized access to router administrative functions

How to Mitigate CVE-2026-2180

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Implement strong authentication credentials and disable default or weak passwords
• Deploy network segmentation to isolate router management interfaces from untrusted networks
• Consider placing the router behind a firewall with strict ingress filtering

Patch Information

As of the last update on 2026-02-10, no official patch has been released by Tenda for this vulnerability. Users should monitor the Tenda official website for firmware updates and security advisories. In the absence of a vendor patch, implementing the recommended workarounds is critical to reduce exposure.

Additional technical details are available through VulDB CTI ID #344883 and the VulDB Submission #749703.

Workarounds

• Disable remote management features if not required for operations
• Limit web interface access to specific IP addresses using access control lists
• Deploy a reverse proxy with input validation in front of the router management interface
• Consider replacing vulnerable devices with alternative hardware if patches are not forthcoming

# Example: Restrict management access via iptables on upstream firewall
# Block external access to router management port (typically 80/443)
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -j DROP

# Allow only trusted management hosts
iptables -I FORWARD -s <TRUSTED_ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s <TRUSTED_ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 443 -j ACCEPT