CVE-2025-9443 Overview
CVE-2025-9443 is a buffer overflow vulnerability affecting Tenda CH22 routers running firmware version 1.0.0.1. The flaw resides in the formeditUserName function within the /goform/editUserName endpoint. Attackers can manipulate the new_account argument to trigger a memory corruption condition [CWE-119]. The vulnerability is remotely exploitable over the network and requires low privileges. Public disclosure of exploit details has occurred through VulDB and a GitHub issue tracker, increasing the risk of opportunistic attacks against exposed devices.
Critical Impact
Remote attackers with low-privileged access can trigger a buffer overflow in the Tenda CH22 router web interface, leading to potential code execution or device compromise affecting confidentiality, integrity, and availability.
Affected Products
- Tenda CH22 router (hardware)
- Tenda CH22 firmware version 1.0.0.1
- Devices exposing the /goform/editUserName web management endpoint
Discovery Timeline
- 2025-08-26 - CVE-2025-9443 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-9443
Vulnerability Analysis
The vulnerability exists in the formeditUserName handler exposed through the /goform/editUserName URI of the Tenda CH22 web management interface. When the handler processes the new_account HTTP parameter, it copies user-supplied data into a fixed-size stack buffer without enforcing length validation. This classic buffer overflow pattern [CWE-119] allows adjacent stack memory, including saved return addresses, to be overwritten.
Successful exploitation can corrupt control flow within the router's HTTP daemon. On MIPS-based Tenda firmware, attackers commonly chain such overflows with return-oriented programming (ROP) gadgets to execute arbitrary commands or spawn a reverse shell on the device. Because the affected component is the router's administrative interface, compromise grants control over network traffic routing, DNS configuration, and downstream client devices.
Root Cause
The root cause is missing bounds checking when handling the new_account parameter inside formeditUserName. The function uses unsafe string copy operations against a finite stack buffer. No input length validation or truncation occurs before the copy, allowing oversized input to corrupt memory beyond the intended buffer boundary.
Attack Vector
The attack is delivered remotely via crafted HTTP POST requests to the /goform/editUserName endpoint. Authentication at a low privilege level is required, meaning any account with access to the management interface can trigger the condition. Devices with the management interface exposed to untrusted networks or default credentials are at elevated risk.
Public technical details are available through the GitHub CVE issue discussion and the VulDB entry.
Detection Methods for CVE-2025-9443
Indicators of Compromise
- HTTP POST requests to /goform/editUserName containing abnormally long new_account parameter values
- Unexpected reboots, crashes, or restarts of the Tenda CH22 HTTP management daemon
- Outbound connections from the router to unknown external IP addresses following administrative login activity
- Modifications to router DNS, DHCP, or routing configuration without authorized administrative changes
Detection Strategies
- Inspect web application firewall and network logs for requests targeting /goform/editUserName with parameter lengths exceeding normal account name sizes
- Deploy network intrusion detection signatures that flag oversized POST bodies directed at Tenda /goform/ endpoints
- Correlate router management interface access from non-administrative source addresses with subsequent configuration drift
Monitoring Recommendations
- Capture and retain HTTP request metadata for all SOHO router management interfaces, including parameter lengths and source addresses
- Monitor for repeated authentication followed by anomalous POST payloads against /goform/ endpoints
- Alert on changes to router firmware version, configuration, or administrative accounts that occur outside scheduled maintenance windows
How to Mitigate CVE-2025-9443
Immediate Actions Required
- Restrict access to the Tenda CH22 management interface to trusted internal management VLANs only, blocking WAN-side exposure
- Change default and weak administrative credentials to strong, unique passwords to reduce the low-privilege attack precondition
- Audit existing CH22 deployments for indicators of prior exploitation, including unexpected accounts or configuration changes
- Place affected devices behind a firewall that filters traffic to /goform/editUserName from untrusted sources
Patch Information
No official vendor patch from Tenda is referenced in the published CVE data at the time of writing. Administrators should monitor the Tenda security resource for firmware updates addressing CVE-2025-9443. If a fixed firmware release becomes available, apply it during the next maintenance window and verify the firmware version after installation.
Workarounds
- Disable remote management of the router from WAN interfaces if not strictly required
- Segment IoT and SOHO router management traffic onto an isolated administrative network
- Replace end-of-life or unsupported Tenda CH22 devices with vendor-supported hardware that receives security updates
- Apply network ACLs that restrict the /goform/editUserName endpoint to known administrative hosts
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
