CVE-2021-38549: Benda Miracase HMUB500 Firmware

Medium severity, CVSS 5.9. EPSS: 1.3% chance of exploitation in the next 30 days.

MIRACASE MHUB500 USB splitters through 2021-08-09, in certain specific use cases in which the device supplies power to audio-output equipment, allow remote attackers to recover speech signals from an LED on the device, via a telescope and an electro-optical sensor, aka a "Glowworm" attack. We assume that the USB splitter supplies power to some speakers. The power indicator LED of the USB splitter is connected directly to the power line, as a result, the intensity of the USB splitter's power indicator LED is correlative to its power consumption. The sound played by the connected speakers affects the USB splitter's power consumption and as a result is also correlative to the light intensity of the LED. By analyzing measurements obtained from an electro-optical sensor directed at the power indicator LED of the USB splitter, we can recover the sound played by the connected speakers.

Affected products

• Benda Miracase HMUB500 Firmware: up to and including 2021-08-09

Published 2021-08-11. Last modified 2026-06-17.