CVE-2026-1329: Tenda AX1803 Buffer Overflow Vulnerability

CVE-2026-1329 Overview

A stack-based buffer overflow vulnerability has been identified in Tenda AX1803 router firmware version 1.0.0.1. The vulnerability exists in the fromGetWifiGuestBasic function within the /goform/WifiGuestSet endpoint. An authenticated remote attacker can manipulate multiple parameters including guestWrlPwd, guestEn, guestSsid, hideSsid, and guestSecurity to trigger a buffer overflow condition, potentially leading to arbitrary code execution or denial of service on the affected device.

Critical Impact

This stack-based buffer overflow vulnerability allows remote authenticated attackers to potentially execute arbitrary code or crash the device by sending specially crafted requests to the Wi-Fi guest network configuration endpoint.

Affected Products

• Tenda AX1803 Firmware Version 1.0.0.1
• Tenda AX1803 devices with the /goform/WifiGuestSet endpoint accessible

Discovery Timeline

• 2026-01-22 - CVE-2026-1329 published to NVD
• 2026-01-22 - Last updated in NVD database

Technical Details for CVE-2026-1329

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The affected function fromGetWifiGuestBasic processes user-supplied input from multiple HTTP parameters without adequate bounds checking. When the router receives a request to the /goform/WifiGuestSet endpoint, the function copies user-controlled data into fixed-size stack buffers.

The vulnerability is particularly concerning because it can be triggered over the network by any authenticated user with access to the router's administrative interface. The exploit has been publicly disclosed, increasing the risk of exploitation in the wild. Multiple parameters are vulnerable, providing attackers with several potential attack vectors to achieve buffer overflow conditions.

Root Cause

The root cause of this vulnerability lies in improper input validation within the fromGetWifiGuestBasic function. The function fails to properly validate the length of input data before copying it to stack-allocated buffers. Specifically, when processing the Wi-Fi guest network configuration parameters (guestWrlPwd, guestEn, guestSsid, hideSsid, guestSecurity), the code does not implement sufficient boundary checks, allowing attackers to provide oversized input that overflows the allocated buffer space on the stack.

Attack Vector

The attack is network-based and requires low-level authentication to the router's administrative interface. An attacker with valid credentials can send a malicious HTTP POST request to the /goform/WifiGuestSet endpoint containing oversized values for any of the vulnerable parameters. By carefully crafting the overflow payload, an attacker may be able to overwrite critical stack data including return addresses, potentially gaining control of program execution.

The vulnerability is exploitable with low complexity as it requires only sending crafted HTTP requests to the affected endpoint. Additional technical details are available in the Notion Security Analysis documentation.

Detection Methods for CVE-2026-1329

Indicators of Compromise

• Unusual or repeated HTTP POST requests to /goform/WifiGuestSet endpoint with abnormally long parameter values
• Router instability, unexpected reboots, or crashes coinciding with administrative access attempts
• Anomalous network traffic patterns from the router's management interface
• Unexpected changes to guest Wi-Fi configuration settings

Detection Strategies

• Monitor HTTP traffic to the router's web management interface for requests containing unusually long parameter values in the guestWrlPwd, guestEn, guestSsid, hideSsid, or guestSecurity fields
• Implement web application firewall (WAF) rules to detect and block requests with parameter lengths exceeding expected maximums
• Deploy network intrusion detection systems (NIDS) with signatures for buffer overflow attempts against Tenda router endpoints
• Review router access logs for suspicious authentication attempts followed by configuration requests

Monitoring Recommendations

• Enable comprehensive logging on the router's management interface if available
• Monitor for unexpected device behavior including crashes, reboots, or configuration changes
• Implement network segmentation to restrict access to router management interfaces
• Deploy SentinelOne Singularity for network visibility to detect exploitation attempts and anomalous device behavior

How to Mitigate CVE-2026-1329

Immediate Actions Required

• Restrict access to the router's administrative interface to trusted IP addresses only
• Implement strong, unique credentials for router administration
• Disable remote management access if not required for operations
• Place the router's management interface on a separate, isolated network segment
• Monitor for firmware updates from Tenda that address this vulnerability

Patch Information

As of the last NVD update on 2026-01-22, no official patch has been released by Tenda. System administrators should monitor the Tenda Official Website for security updates addressing this vulnerability. Additional vulnerability tracking information is available through VulDB #342305.

Workarounds

• Limit administrative interface access to localhost or trusted management stations only
• Use access control lists (ACLs) to restrict which IP addresses can reach the /goform/ endpoints
• Consider deploying a reverse proxy with input validation in front of the management interface
• If guest Wi-Fi functionality is not required, disable it entirely to reduce attack surface

# Configuration example: Restrict management access via iptables (on upstream firewall)
# Block external access to router management on port 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 subnet
iptables -I FORWARD -s TRUSTED_MGMT_SUBNET -d ROUTER_IP -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s TRUSTED_MGMT_SUBNET -d ROUTER_IP -p tcp --dport 443 -j ACCEPT