CVE-2026-5154: Tenda CH22 Buffer Overflow Vulnerability

CVE-2026-5154 Overview

CVE-2026-5154 is a stack-based buffer overflow vulnerability affecting Tenda CH22 routers running firmware version 1.0.0.1. The flaw resides in the fromSetCfm function within the /goform/setcfm endpoint, which is part of the device's Parameter Handler component. Attackers can manipulate the funcname argument over the network to corrupt stack memory. The vulnerability has been publicly disclosed, and exploit details are available through third-party vulnerability databases. Successful exploitation can lead to arbitrary code execution or service disruption on the affected router.

Critical Impact

Remote attackers with low-level authentication can trigger a stack overflow in the Tenda CH22 web management interface, potentially executing arbitrary code on the device.

Affected Products

• Tenda CH22 router (hardware)
• Tenda CH22 firmware version 1.0.0.1
• /goform/setcfm Parameter Handler component

Discovery Timeline

• 2026-03-30 - CVE-2026-5154 published to the National Vulnerability Database (NVD)
• 2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-5154

Vulnerability Analysis

The vulnerability is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer). It exists in the fromSetCfm function exposed by the /goform/setcfm HTTP endpoint on the Tenda CH22 router's management interface. The function processes the funcname parameter without enforcing proper bounds checking before writing it into a fixed-size stack buffer.

Attackers reaching the management interface over the network can submit an oversized funcname value to overwrite adjacent stack memory. This corruption can overwrite the saved return address and redirect execution flow. On embedded MIPS or ARM router platforms like the CH22, such overflows commonly enable arbitrary code execution because protections such as stack canaries and address space layout randomization (ASLR) are typically absent.

Root Cause

The root cause is the absence of input length validation on the funcname argument before it is copied into a stack-allocated buffer inside fromSetCfm. The handler trusts attacker-controlled input from HTTP request parameters, resulting in classic stack-based memory corruption when the input exceeds the buffer's capacity.

Attack Vector

Exploitation requires network access to the router's web management interface and low-level privileges. An attacker sends a crafted HTTP request to /goform/setcfm with a funcname parameter containing an oversized payload. The overflow overwrites control data on the stack, enabling denial of service or arbitrary code execution within the context of the web server process, which typically runs with elevated privileges on the device.

No verified proof-of-concept code is included here. Refer to the GitHub Vulnerability Documentation and the VulDB #354186 Vulnerability entry for technical details.

Detection Methods for CVE-2026-5154

Indicators of Compromise

• HTTP POST requests to /goform/setcfm containing abnormally long funcname parameter values
• Unexpected reboots, crashes, or unresponsiveness of the Tenda CH22 web management service
• Outbound network connections from the router to unknown hosts following suspicious management-interface traffic
• New or modified configuration entries that do not correspond to authorized administrative actions

Detection Strategies

• Inspect web server and management interface logs for requests targeting /goform/setcfm with parameter lengths exceeding expected bounds
• Deploy network intrusion detection signatures that match oversized funcname values in HTTP traffic destined for CH22 devices
• Correlate router crash events or watchdog reboots with preceding HTTP traffic to the management endpoint

Monitoring Recommendations

• Restrict and monitor administrative access to router management interfaces from internal network segments only
• Forward router syslog data to a centralized logging platform for retention and correlation
• Alert on repeated authentication attempts or malformed requests against /goform/* endpoints

How to Mitigate CVE-2026-5154

Immediate Actions Required

• Disable remote (WAN-side) management on the Tenda CH22 router until a vendor patch is verified
• Restrict access to the local management interface using firewall rules or VLAN segmentation
• Rotate administrative credentials and audit existing user accounts on the device
• Monitor the Tenda Official Website for firmware updates addressing this issue

Patch Information

At the time of publication, no official vendor patch has been linked in the CVE record for Tenda CH22 firmware 1.0.0.1. Administrators should track the VulDB #354186 Vulnerability entry and the vendor's support channels for firmware updates. If a patched firmware version becomes available, apply it through the device's standard upgrade workflow after validating the image hash.

Workarounds

• Place the router behind a network access control list that blocks untrusted hosts from reaching the HTTP management interface
• Enforce strong, unique administrator passwords to limit pre-authentication attack surface
• Consider replacing end-of-support or unpatched CH22 units with current, vendor-supported hardware
• Segment IoT and infrastructure devices from user and server networks to limit lateral movement after compromise