CVE-2026-5154: Tenda CH22 Buffer Overflow Vulnerability

CVE-2026-5154 Overview

A stack-based buffer overflow vulnerability has been identified in Tenda CH22 firmware versions 1.0.0.1 and 1.If. The vulnerability exists in the fromSetCfm function within the /goform/setcfm endpoint of the Parameter Handler component. When the funcname argument is manipulated with malicious input, it triggers a stack-based buffer overflow condition that can be exploited remotely over the network.

Critical Impact

Remote attackers can exploit this vulnerability to potentially achieve arbitrary code execution on affected Tenda CH22 devices, compromising device integrity, confidentiality, and availability without requiring physical access.

Affected Products

• Tenda CH22 Firmware Version 1.0.0.1
• Tenda CH22 Firmware Version 1.If

Discovery Timeline

• 2026-03-30 - CVE-2026-5154 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2026-5154

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), specifically manifesting as a stack-based buffer overflow. The affected function fromSetCfm in the /goform/setcfm endpoint fails to properly validate the length of user-supplied input through the funcname parameter before copying it to a stack-allocated buffer.

When an attacker supplies an oversized value for the funcname argument, the function writes beyond the allocated buffer boundaries on the stack. This memory corruption can overwrite critical stack data including return addresses and saved frame pointers, potentially allowing an attacker to redirect program execution to malicious code.

The vulnerability is remotely exploitable over the network and requires low-privilege access to trigger. The exploit has been publicly disclosed, increasing the risk of active exploitation in the wild.

Root Cause

The root cause of this vulnerability lies in the improper handling of user-supplied input within the fromSetCfm function. The code fails to implement adequate bounds checking when processing the funcname parameter, allowing attackers to provide input that exceeds the expected buffer size. This absence of input validation is a common weakness in embedded device firmware where memory safety practices may not be rigorously enforced.

Attack Vector

The attack is conducted remotely over the network by sending specially crafted HTTP requests to the /goform/setcfm endpoint on vulnerable Tenda CH22 devices. An attacker with low-privilege network access can manipulate the funcname parameter to include an oversized payload that triggers the buffer overflow condition.

The exploitation flow typically involves:

1. Identifying a vulnerable Tenda CH22 device accessible on the network
2. Crafting an HTTP request to the /goform/setcfm endpoint
3. Including a malicious funcname parameter with payload exceeding buffer boundaries
4. Overwriting stack memory to gain control of program execution

For technical details and proof-of-concept information, refer to the GitHub Vulnerability Documentation and VulDB Vulnerability #354186.

Detection Methods for CVE-2026-5154

Indicators of Compromise

• Unusual HTTP POST requests to /goform/setcfm containing abnormally large funcname parameter values
• Device crashes or unexpected reboots following web management interface interactions
• Anomalous network traffic patterns originating from or targeting Tenda CH22 devices on common management ports
• Evidence of unauthorized configuration changes or firmware modifications

Detection Strategies

• Implement network intrusion detection rules to identify HTTP requests to /goform/setcfm with oversized parameters
• Monitor web server logs on Tenda CH22 devices for requests containing suspicious payload patterns in the funcname field
• Deploy network anomaly detection to identify unusual traffic volumes or patterns to embedded device management interfaces
• Configure SentinelOne agents on network management systems to detect exploitation attempts against IoT infrastructure

Monitoring Recommendations

• Enable logging for all web management interface access on Tenda CH22 devices
• Implement network segmentation to isolate IoT and embedded devices from critical infrastructure
• Establish baseline network behavior for Tenda devices and alert on deviations
• Regularly audit device configurations and firmware versions against known vulnerable releases

How to Mitigate CVE-2026-5154

Immediate Actions Required

• Restrict network access to the Tenda CH22 web management interface to trusted IP addresses only
• Place affected devices behind a firewall and disable remote management capabilities if not required
• Monitor network traffic for exploitation attempts targeting the /goform/setcfm endpoint
• Consider temporarily taking vulnerable devices offline if they are exposed to untrusted networks

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor the Tenda Official Website for firmware updates and security advisories. Additional technical details are available through VulDB Submission ID #780206 and the VulDB CTI Details.

Workarounds

• Disable the web management interface entirely if device management can be performed through alternative methods
• Implement network-level access controls using ACLs to restrict access to the /goform/setcfm endpoint
• Deploy a web application firewall (WAF) or reverse proxy to filter malicious requests before they reach the device
• Enable HTTPS-only access if supported to prevent network-based interception of management traffic

# Example firewall rule to restrict access to Tenda CH22 management interface
# Replace 192.168.1.100 with your Tenda CH22 device IP
# Replace 10.0.0.0/24 with your trusted management network

# iptables example - block external access to web management
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -j DROP
iptables -A FORWARD -s 10.0.0.0/24 -d 192.168.1.100 -p tcp --dport 80 -j ACCEPT