CVE-2025-11418: Tenda CH22 Buffer Overflow Vulnerability

CVE-2025-11418 Overview

A critical stack-based buffer overflow vulnerability has been identified in Tenda CH22 routers running firmware version 1.0.0.1 and earlier. This security flaw exists in the formWrlsafeset function within the HTTP Request Handler component, specifically when processing requests to /goform/AdvSetWrlsafeset. An attacker can exploit this vulnerability by manipulating the mit_ssid_index argument, leading to a stack-based buffer overflow condition that can be triggered remotely over the network.

The exploit has been publicly disclosed, increasing the risk of active exploitation in the wild. Network-accessible routers running vulnerable firmware are at immediate risk.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to potentially execute arbitrary code, crash the device, or gain unauthorized control over the affected Tenda CH22 router without authentication.

Affected Products

• Tenda CH22 Firmware versions up to and including 1.0.0.1
• Tenda CH22 Hardware devices running vulnerable firmware

Discovery Timeline

• October 8, 2025 - CVE-2025-11418 published to NVD
• October 9, 2025 - Last updated in NVD database

Technical Details for CVE-2025-11418

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), which indicates insufficient boundary checking when handling memory operations. The vulnerable function formWrlsafeset fails to properly validate the length of data supplied through the mit_ssid_index parameter before copying it to a fixed-size stack buffer.

When a malicious HTTP request is sent to the /goform/AdvSetWrlsafeset endpoint with an oversized or specially crafted mit_ssid_index value, the function writes beyond the allocated stack buffer boundaries. This memory corruption can overwrite critical stack elements including saved return addresses and function pointers.

The network-accessible nature of this vulnerability combined with no authentication requirements makes it particularly dangerous for internet-exposed devices. Successful exploitation could allow an attacker to achieve remote code execution with the privileges of the HTTP service, typically running as root on embedded devices.

Root Cause

The root cause stems from improper input validation in the formWrlsafeset function when processing the mit_ssid_index argument from incoming HTTP requests. The function allocates a fixed-size buffer on the stack but does not enforce proper bounds checking before copying user-supplied data. This classic buffer overflow pattern allows attackers to supply input exceeding the expected buffer size, corrupting adjacent memory on the stack.

Attack Vector

The attack is conducted remotely over the network through crafted HTTP POST requests to the vulnerable endpoint. An attacker sends a malicious request to /goform/AdvSetWrlsafeset with an oversized mit_ssid_index parameter value. Since no authentication is required to reach this endpoint, any network-adjacent attacker—or remote attacker if the device's web interface is exposed to the internet—can attempt exploitation.

The attack flow involves:

1. Identifying a vulnerable Tenda CH22 device on the network
2. Crafting an HTTP POST request targeting /goform/AdvSetWrlsafeset
3. Including a malicious payload in the mit_ssid_index parameter designed to overflow the stack buffer
4. Potentially achieving code execution or causing a denial of service condition

Technical details regarding the exploit have been publicly disclosed. For additional information, refer to the GitHub CVE Issue Discussion and VulDB #327354.

Detection Methods for CVE-2025-11418

Indicators of Compromise

• Unusual HTTP POST requests to /goform/AdvSetWrlsafeset endpoint with abnormally large mit_ssid_index parameter values
• Device crashes or unexpected reboots indicating potential exploitation attempts
• Suspicious network traffic patterns targeting the router's web management interface
• Anomalous outbound connections from the router to unknown external hosts

Detection Strategies

• Deploy network intrusion detection rules to monitor for oversized HTTP requests targeting /goform/AdvSetWrlsafeset
• Implement web application firewall rules to filter requests containing excessively long parameter values
• Monitor router logs for repeated access attempts to the vulnerable endpoint
• Use SentinelOne Singularity to detect anomalous process behavior on network segments containing vulnerable devices

Monitoring Recommendations

• Enable verbose logging on the Tenda CH22 web interface if available
• Monitor network traffic for HTTP requests to goform endpoints with unusual payload sizes
• Set up alerts for device availability to detect potential denial of service conditions
• Regularly audit network perimeter for exposed router management interfaces

How to Mitigate CVE-2025-11418

Immediate Actions Required

• Restrict network access to the Tenda CH22 web management interface to trusted IP addresses only
• Disable remote management features if not required for operations
• Implement network segmentation to isolate vulnerable devices from untrusted networks
• Monitor for firmware updates from Tenda and apply patches when available

Patch Information

As of the last update on October 9, 2025, no official patch information has been released by Tenda. Organizations should monitor the Tenda Official Website for security advisories and firmware updates addressing this vulnerability. Given the public disclosure of exploit details, prioritize mitigation through network controls until an official patch becomes available.

Workarounds

• Configure firewall rules to block external access to ports 80 and 443 on the affected device
• Use VPN or other secure tunneling methods for remote administration rather than direct web interface access
• Consider replacing affected devices with alternatives that have active security support if patches are not forthcoming
• Implement network access control lists (ACLs) to restrict which hosts can communicate with the router's management interface

# Example iptables rules to restrict access to router management interface
# Apply on upstream firewall or gateway device

# Block external access to HTTP management port
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_SUBNET> -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s <TRUSTED_SUBNET> -d <ROUTER_IP> -p tcp --dport 443 -j ACCEPT