CVE-2021-38549: MIRACASE MHUB500 USB splitters through 2021-08-09, in certain specific use cases in which the device supplies

Q: How do I fix CVE-2021-38549?

miracase hmub500 firmware: upgrade to newer than 2021-08-09. Exact commands for each OS are on this page.

Q: Is CVE-2021-38549 being exploited?

CVE-2021-38549 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-38549 affect?

CVE-2021-38549 affects miracase hmub500 firmware. Severity is medium (CVSS 5.9). 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 a

Q: How urgent is CVE-2021-38549?

Priority 48/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

MEDIUM 5.9REMOTEUPGRADE

CVE-2021-38549 is a medium-severity flaw (CVSS 5.9) affecting miracase hmub500 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 resu

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	1.3% (top 30%)
CISA exploited list	No
Published	2021-08-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: benda

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-08-11 16:15 UTCPublished CVE record published
2026-06-17 04:02 UTCUpdated Record last modified

benda miracase hmub500 firmware UPGRADE

Affected: <= 2021-08-09

Fixed in: newer than 2021-08-09

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-38549?

miracase hmub500 firmware: upgrade to newer than 2021-08-09. Exact commands for each OS are on this page.

Is CVE-2021-38549 being exploited?

CVE-2021-38549 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-38549 affect?

CVE-2021-38549 affects miracase hmub500 firmware. Severity is medium (CVSS 5.9). 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 a

How urgent is CVE-2021-38549?

Priority 48/100. Public exploit reference; Remotely exploitable, no login, no user action

References

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