CVE-2025-12273: Tenda CH22 Buffer Overflow Vulnerability

CVE-2025-12273 Overview

A buffer overflow vulnerability has been identified in Tenda CH22 firmware version 1.0.0.1. The vulnerability affects the fromwebExcptypemanFilter function located in the /goform/webExcptypemanFilter file. An attacker can exploit this flaw by manipulating the page argument, leading to a buffer overflow condition. This vulnerability can be exploited remotely over the network, making it particularly dangerous for exposed devices. The exploit has been made publicly available, increasing the risk of active exploitation.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow to potentially execute arbitrary code, compromise device integrity, and gain unauthorized access to the network device and connected infrastructure.

Affected Products

• Tenda CH22 Firmware version 1.0.0.1
• Tenda CH22 Hardware (all versions)

Discovery Timeline

• October 27, 2025 - CVE-2025-12273 published to NVD
• February 24, 2026 - Last updated in NVD database

Technical Details for CVE-2025-12273

Vulnerability Analysis

This buffer overflow vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) exists in the web management interface of the Tenda CH22 router. The vulnerable function fromwebExcptypemanFilter fails to properly validate the length of user-supplied input passed through the page parameter before copying it into a fixed-size buffer.

When an authenticated attacker sends a specially crafted HTTP request to the /goform/webExcptypemanFilter endpoint with an oversized page argument, the function writes beyond the allocated buffer boundaries. This memory corruption can overwrite adjacent memory regions, potentially including return addresses or function pointers, enabling code execution in the context of the router's firmware.

The network-accessible nature of this vulnerability combined with the low authentication requirements makes it a significant threat for any Tenda CH22 devices exposed to untrusted networks.

Root Cause

The root cause is improper input validation in the fromwebExcptypemanFilter function. The code does not verify that the length of the page parameter falls within acceptable bounds before processing, allowing attackers to supply maliciously oversized input that exceeds the buffer's allocated memory space. This represents a classic buffer overflow pattern commonly found in embedded device firmware where memory-safe programming practices may not be consistently applied.

Attack Vector

The attack can be executed remotely over the network by sending a crafted HTTP POST request to the /goform/webExcptypemanFilter endpoint. The attacker manipulates the page argument with an excessively long string to trigger the buffer overflow. While low-level privileges are required, no user interaction is necessary to exploit this vulnerability.

The vulnerability mechanism involves sending an HTTP request to the web management interface with a malformed page parameter. The fromwebExcptypemanFilter function processes this input without proper bounds checking, writing the oversized data into a fixed-size stack or heap buffer. This overflow corrupts adjacent memory, potentially allowing the attacker to hijack program execution flow. For detailed technical analysis, refer to the GitHub Issue on CVE and VulDB #329945.

Detection Methods for CVE-2025-12273

Indicators of Compromise

• Unusual HTTP POST requests to /goform/webExcptypemanFilter containing abnormally long page parameter values
• Unexpected router reboots or crashes potentially indicating exploitation attempts
• Anomalous network traffic patterns originating from or destined to the Tenda CH22 management interface
• Unauthorized configuration changes on the router device

Detection Strategies

• Monitor HTTP traffic for requests to the /goform/webExcptypemanFilter endpoint with page parameters exceeding normal length thresholds
• Implement intrusion detection system (IDS) rules to alert on buffer overflow attack signatures targeting Tenda devices
• Review router access logs for repeated authentication attempts followed by requests to the vulnerable endpoint
• Deploy network segmentation to isolate router management interfaces from untrusted networks

Monitoring Recommendations

• Enable logging on all Tenda CH22 devices and centralize logs for analysis
• Set up alerts for any access attempts to the web management interface from external IP addresses
• Monitor device performance metrics for sudden CPU or memory spikes that may indicate exploitation
• Implement network traffic analysis tools to detect anomalous patterns associated with buffer overflow exploitation attempts

How to Mitigate CVE-2025-12273

Immediate Actions Required

• Restrict access to the Tenda CH22 web management interface to trusted internal networks only
• Implement firewall rules to block external access to the device's management ports (typically HTTP/HTTPS)
• Consider disabling remote management functionality until a patch is available
• Monitor devices for signs of compromise and isolate any potentially affected systems

Patch Information

At the time of this advisory, no official patch from Tenda has been referenced in the available vulnerability data. Organizations should monitor the Tenda Official Website for firmware updates addressing this vulnerability. Until a patch is released, implementing the recommended workarounds is critical for reducing exposure risk.

Workarounds

• Disable remote management access to the Tenda CH22 device entirely
• Place the router management interface behind a VPN to limit exposure
• Implement strict access control lists (ACLs) restricting management interface access to specific trusted IP addresses
• Consider replacing affected devices with alternative hardware if the vendor does not provide timely patches

# Example firewall rule to block external access to management interface
# Adjust interface and IP ranges according to your network configuration
iptables -A INPUT -i eth0 -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -i eth0 -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP