CVE-2025-65202 Overview
CVE-2025-65202 is an authenticated OS command injection vulnerability in the TRENDnet TEW-657BRM wireless router running firmware version 1.00.1. The flaw resides in the setup.cgi binary, which fails to sanitize the HTTP parameters command, todo, and next_file before passing them to a system shell. An authenticated attacker on an adjacent network can inject arbitrary shell commands that execute with root privileges. The weakness is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command).
Critical Impact
Successful exploitation yields root-level command execution on affected routers, enabling full device takeover, traffic interception, and use of the router as a foothold into the internal network.
Affected Products
- TRENDnet TEW-657BRM hardware router
- TRENDnet TEW-657BRM firmware version 1.00.1
- Deployments exposing the web management interface (setup.cgi) to authenticated users on adjacent networks
Discovery Timeline
- 2025-11-26 - CVE-2025-65202 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-65202
Vulnerability Analysis
The TEW-657BRM administrative interface exposes a CGI binary named setup.cgi that handles configuration actions submitted via HTTP. Three request parameters — command, todo, and next_file — are passed to an underlying shell invocation without adequate input neutralization. Attackers can append shell metacharacters such as ;, |, or backticks to inject additional commands. Because CGI processes on this device run as root, injected commands inherit full administrative privileges on the embedded Linux system.
Exploitation requires prior authentication and network adjacency, but consumer routers frequently retain default or weak credentials. The EPSS score of 6.69% places this vulnerability in the 93rd percentile for near-term exploitation likelihood.
Root Cause
The root cause is missing input validation and unsafe construction of shell command strings inside setup.cgi. User-controlled HTTP parameters are concatenated directly into commands executed by system() or an equivalent shell interface. This pattern is a textbook CWE-78 OS command injection.
Attack Vector
An authenticated attacker sends a crafted HTTP request to setup.cgi on the router's management interface. The request carries a malicious payload in the command, todo, or next_file parameter that terminates the intended command and appends attacker-controlled shell instructions. The router executes the injected payload as root, allowing arbitrary binary execution, persistence installation, credential extraction, and DNS or routing manipulation. Proof-of-concept material is available in the TEW-657BRM PoC Repository.
Detection Methods for CVE-2025-65202
Indicators of Compromise
- HTTP requests to /setup.cgi containing shell metacharacters (;, |, &, backticks, $()) in the command, todo, or next_file parameters
- Unexpected outbound connections initiated by the router to attacker-controlled infrastructure
- Modified startup scripts, cron entries, or new binaries in writable firmware partitions
- Unusual DNS resolver or routing table changes on the affected device
Detection Strategies
- Inspect web server and CGI access logs on the router for requests to setup.cgi carrying suspicious parameter values
- Deploy network intrusion detection signatures that flag command injection patterns targeting embedded CGI endpoints
- Baseline expected management-interface traffic and alert on connections from unusual source addresses on the LAN or Wi-Fi segments
Monitoring Recommendations
- Forward router syslog and management-plane logs to a centralized logging or SIEM platform for correlation
- Monitor for authentication events on the router web UI, particularly repeated logins from new hosts
- Track outbound traffic from the router itself; a healthy consumer router rarely initiates arbitrary outbound sessions
How to Mitigate CVE-2025-65202
Immediate Actions Required
- Restrict access to the router's web management interface to trusted wired hosts only and disable remote administration
- Change the default administrator password and enforce a strong, unique credential
- Segment the vulnerable router away from sensitive internal assets until it can be replaced or patched
- Audit the device for unauthorized configuration changes, additional user accounts, and modified firmware
Patch Information
No vendor advisory or firmware update is listed in the NVD entry for CVE-2025-65202 at the time of publication. The TEW-657BRM is a legacy consumer router and may no longer receive security updates from TRENDnet. Organizations still operating this hardware should plan for replacement with a currently supported model.
Workarounds
- Disable the web administration interface on wireless interfaces so setup.cgi is unreachable from Wi-Fi clients
- Place the router behind an upstream firewall that blocks direct HTTP access to the management interface from untrusted segments
- Decommission the device and migrate to a supported router that receives active firmware maintenance
# Example: block LAN-side access to the router management UI at an upstream firewall
iptables -A FORWARD -p tcp -d <router-ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router-ip> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
