# CVE-2026-5355: Trendnet TEW-657BRM command injection in setup.cgi

Source: https://junglewise.ai/threats/cve-2026-5355-trendnet-tew-657brm-command-injection-in-setup-cgi  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-02. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-5355 · Severity: medium · CVSS 6.3 · Published 2026-04-02

A vulnerability exists in the Trendnet TEW-657BRM router, an older networking device used for internet connectivity. An attacker can remotely take full control of the device by sending a specially crafted request to its management interface. This could lead to a complete loss of privacy for network traffic or the device being used as a foothold for further attacks. Note that this product reached its end-of-life in 2011 and is no longer supported by the manufacturer.

Technologies: [TRENDnet Tew-657brm](https://junglewise.ai/threats/technologies/tew-657brm), [TRENDnet Tew-657brm Firmware](https://junglewise.ai/threats/technologies/tew-657brm-firmware). Vendors: [TRENDnet](https://junglewise.ai/threats/vendors/trendnet).

## Quick answers

**Is CVE-2026-5355 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5355 being exploited in the wild.

**How severe is CVE-2026-5355?** Medium severity, with a CVSS score of 6.3, published 2 April 2026.

**Which products and versions are affected?** TRENDnet Tew-657brm 1.00.1.

**Is there a fix for CVE-2026-5355?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-5355 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5355?** Check whether you run TRENDnet Tew-657brm or TRENDnet Tew-657brm Firmware at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An OS command injection vulnerability exists in the Trendnet TEW-657BRM router running firmware version 1.00.1. The flaw is located within the vpn_drop function in the /setup.cgi component. The root cause is the improper neutralization of the 'policy_name' POST parameter before it is passed to a system command execution function. A remote attacker with low privileges (authenticated access to the web interface) can exploit this by injecting shell commands into the parameter, leading to arbitrary code execution with the privileges of the web server. A public proof-of-concept exists. The vendor has stated the product is end-of-life and will not receive a patch.

## Affected products

- Trendnet TEW-657BRM 1.00.1

## Timeline

- 2011-06-23: other: Product reached End-of-Life (EOL) status
- 2026-04-02: disclosed: Vulnerability disclosed and exploit made public
- 2026-04-02: advisory

## References

- [https://github.com/panda666-888/vuls/blob/main/trendnet/tew-657brm/vpn_drop.md](https://github.com/panda666-888/vuls/blob/main/trendnet/tew-657brm/vpn_drop.md)
- [https://vuldb.com/submit/781569](https://vuldb.com/submit/781569)
- [https://vuldb.com/vuln/354708](https://vuldb.com/vuln/354708)
- [https://vuldb.com/vuln/354708/cti](https://vuldb.com/vuln/354708/cti)

## Related threats

- [Trendnet TEW-657BRM command injection in setup.cgi](https://junglewise.ai/threats/cve-2026-5354-trendnet-tew-657brm-command-injection-in-setup-cgi)
- [Trendnet TEW-657BRM command injection in setup.cgi](https://junglewise.ai/threats/cve-2026-5353-trendnet-tew-657brm-command-injection-in-setup-cgi)
- [Trendnet TEW-657BRM OS command injection in setup.cgi](https://junglewise.ai/threats/cve-2026-5352-trendnet-tew-657brm-os-command-injection-in-setup-cgi)
- [Trendnet TEW-657BRM OS command injection in setup.cgi](https://junglewise.ai/threats/cve-2026-5351-trendnet-tew-657brm-os-command-injection-in-setup-cgi)
- [Trendnet TEW-657BRM stack overflow in setup.cgi](https://junglewise.ai/threats/cve-2026-5350-trendnet-tew-657brm-stack-overflow-in-setup-cgi)