CVE-2021-38549Public exploit

Speech recovery via power-LED optical emissions

Published Aug 11, 2021 · Updated Aug 4, 2024

Information disclosure in MIRACASE MHUB500 USB splitters through 2021-08-09 allows remote attackers to recover speech via the power LED. The LED is wired directly to the splitter's power line, so speaker-driven power fluctuations modulate its light intensity and expose the audio signal. Exploitation requires the splitter to power audio-output equipment plus line of sight and a telescope with an electro-optical sensor; it reveals played audio without altering the device.

CVSS severity5.9
Medium
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in MIRACASE MHUB500 USB splitters through 2021-08-09 allows remote attackers to recover speech via the power LED. The LED is wired directly to the splitter's power line, so speaker-driven power fluctuations modulate its light intensity and expose the audio signal. Exploitation requires the splitter to power audio-output equipment plus line of sight and a telescope with an electro-optical sensor; it reveals played audio without altering the device.

The record

CVE
CVE-2021-38549
Published
Aug 11, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1123
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1123Audio Capture

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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