Zyxel GS1900 Patch Fails to Block Zero-Day Exploit Allowing Root Command Execution

Researchers at Binarly discovered that a previous patch for Zyxel GS1900 network switches did not fully address a zero-day exploit. The exploit allows unauthorized command execution on the switch via its web management interface without requiring login credentials. Zyxel has now released new firmware for 10 GS1900 models to properly fix the vulnerability. The earlier patch, version 2.90, was insufficient to block the exploit. This means that switches that only received the earlier fix are still vulnerable to attack. A new firmware update is necessary to close the security hole.