CVE-2025-43989 Overview
CVE-2025-43989 is an OS command injection vulnerability [CWE-78] affecting Shenzhen Tuoshi NR500-EA devices running firmware version RG500UEAABxCOMSLICv3.4.2731.16.43. The /goform/formJsonAjaxReq POST endpoint mishandles the set_timesetting action with the ntpserver0 parameter, which is passed directly into a system command. An unauthenticated attacker can bypass session validation by setting a username=admin cookie, then inject arbitrary operating system commands through the ntpserver0 value. Successful exploitation grants command execution on the router with the privileges of the web service.
Critical Impact
Unauthenticated attackers can execute arbitrary OS commands on affected NR500-EA devices by exploiting a cookie-based authentication bypass combined with unsanitized input to a system command.
Affected Products
- Shenzhen Tuoshi NR500-EA industrial cellular router
- Firmware version RG500UEAABxCOMSLICv3.4.2731.16.43
- Web management interface exposing /goform/formJsonAjaxReq
Discovery Timeline
- 2025-08-13 - CVE-2025-43989 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-43989
Vulnerability Analysis
The vulnerability resides in the request handler for /goform/formJsonAjaxReq on the NR500-EA management web server. When the endpoint receives a POST request with action=set_timesetting, it reads the ntpserver0 parameter and concatenates the value into an OS command string used to configure Network Time Protocol (NTP) synchronization. The application does not sanitize or validate the parameter, so shell metacharacters such as ;, |, and backticks are interpreted by the underlying shell.
The endpoint compounds the issue with a weak session enforcement model. Rather than verifying a signed session token, the handler accepts any request that presents a username=admin cookie value. An attacker can craft that cookie without providing credentials, effectively removing the authentication barrier.
Root Cause
The root cause is improper neutralization of special elements used in an OS command [CWE-78]. User-controlled input from the ntpserver0 parameter reaches a shell invocation without input filtering, allowlisting, or safe API usage such as execve with argument arrays.
Attack Vector
The attack vector is remote over the network. An attacker sends a single crafted HTTP POST to /goform/formJsonAjaxReq with the username=admin cookie, action=set_timesetting, and a malicious ntpserver0 payload containing shell command separators. The injected commands run in the context of the web service, which on embedded routers typically runs as root. Public technical details are documented in the GitHub CVE writeup for CVE-2025-43989.
Detection Methods for CVE-2025-43989
Indicators of Compromise
- HTTP POST requests to /goform/formJsonAjaxReq containing action=set_timesetting and shell metacharacters (;, |, &, backticks, $()) in the ntpserver0 parameter
- Requests to the management interface presenting a Cookie: username=admin header without a preceding authenticated login flow
- Unexpected outbound connections from the router to attacker-controlled infrastructure following NTP configuration changes
- New processes or persistence artifacts on the device, such as modified /etc/init.d/ scripts or cron entries
Detection Strategies
- Inspect web server and reverse proxy logs for POST requests to /goform/formJsonAjaxReq and alert on non-hostname characters within the ntpserver0 value
- Deploy network intrusion detection signatures that match the combination of the vulnerable path and cookie-based username=admin sessions
- Correlate configuration change events on the router with subsequent process execution or outbound traffic anomalies
Monitoring Recommendations
- Restrict and log all access to the router management interface, treating any exposure to untrusted networks as high risk
- Baseline normal NTP server values and alert on out-of-policy changes pushed through the web UI
- Forward router syslog and web access logs to a centralized analytics platform for retention and query
How to Mitigate CVE-2025-43989
Immediate Actions Required
- Remove the NR500-EA management interface from any untrusted or internet-facing network segment
- Enforce network-level access control lists so only trusted administrative hosts can reach the router web interface
- Audit device configurations and running processes for signs of prior exploitation, including unexpected NTP server entries
- Contact Shenzhen Tuoshi support to confirm availability of a firmware update addressing the formJsonAjaxReq handler
Patch Information
At the time of publication, no vendor advisory or fixed firmware version is referenced in the NVD entry for CVE-2025-43989. Organizations should track the GitHub CVE repository for Tuoshi and vendor communications for a firmware release addressing the command injection and the cookie-based authentication bypass.
Workarounds
- Block external access to TCP ports serving the router management UI using upstream firewalls or ISP-provided filtering
- Place the device behind a VPN gateway so administrative traffic requires authenticated tunnel access
- Where feasible, disable the web management service and manage the device through an out-of-band console interface
- Monitor for and drop HTTP requests that include a username=admin cookie without a corresponding authenticated session state
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
