CVE-2021-38543

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under NVD CVSS v3. EPSS exploit probability: 1.3% (69th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1.3%CVSS: 5.9Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

TP-Link UE330 USB splitter devices 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.

CVSS v3
5.9
EG Score
5.9MEDIUMmedium confidence
EG Risk
32
EG Risk 32/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation1% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
1.3%
EPSS %ILE
69th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 11, 2021

Last Modified

November 21, 2024

References (2)

Data Freshness Timeline

(refreshed 7× in last 7d / 32× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 175 total refreshes for this CVE.

  1. 2026-10-05 17:40 UTCEPSS rescore
  2. 2026-10-04 23:19 UTCEPSS rescore
  3. 2026-10-03 14:22 UTCEPSS rescore
  4. 2026-10-01 19:46 UTCEPSS rescore
  5. 2026-09-30 15:39 UTCEG score recompute
  6. 2026-09-30 15:00 UTCEPSS rescore
  7. 2026-09-29 15:15 UTCEPSS rescore
  8. 2026-09-28 13:47 UTCEPSS rescore
  9. 2026-09-27 13:41 UTCEPSS rescore
  10. 2026-09-26 15:54 UTCEPSS rescore
  11. 2026-09-26 00:21 UTCEPSS rescore
  12. 2026-09-24 14:00 UTCEPSS rescore
  13. 2026-09-23 13:44 UTCEPSS rescore
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  15. 2026-09-21 20:28 UTCEPSS rescore
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  17. 2026-09-20 20:12 UTCEPSS rescore
  18. 2026-09-19 15:38 UTCEPSS rescore
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  22. 2026-09-16 14:05 UTCEPSS rescore
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  24. 2026-09-15 03:06 UTCEPSS rescore
  25. 2026-09-13 16:43 UTCEPSS rescore
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  1. 2026-09-12 14:57 UTCEPSS rescore
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  3. 2026-09-11 09:33 UTCEPSS rescore
  4. 2026-09-08 21:56 UTCEPSS rescore
  5. 2026-09-07 15:58 UTCEPSS rescore
  6. 2026-09-06 13:45 UTCEPSS rescore
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  8. 2026-09-05 15:25 UTCEPSS rescore
  9. 2026-09-04 13:57 UTCEPSS rescore
  10. 2026-09-04 05:03 UTCEPSS rescore
  11. 2026-09-02 14:08 UTCEPSS rescore
  12. 2026-09-01 13:50 UTCEPSS rescore
  13. 2026-08-30 19:14 UTCEPSS rescore
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  16. 2026-08-28 21:37 UTCEPSS rescore
  17. 2026-08-27 14:22 UTCEPSS rescore
  18. 2026-08-26 14:42 UTCEPSS rescore
  19. 2026-08-25 13:46 UTCEPSS rescore
  20. 2026-08-24 14:13 UTCEPSS rescore
  21. 2026-08-23 00:16 UTCEPSS rescore
  22. 2026-08-21 23:46 UTCEPSS rescore
  23. 2026-08-20 22:52 UTCEPSS rescore
  24. 2026-08-19 17:01 UTCEPSS rescore
  25. 2026-08-18 13:45 UTCEPSS rescore
  26. 2026-08-17 13:44 UTCEPSS rescore
  27. 2026-08-16 14:53 UTCEPSS rescore
  28. 2026-08-16 02:11 UTCEPSS rescore
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  30. 2026-08-15 01:27 UTCEPSS rescore
  31. 2026-08-13 21:57 UTCEPSS rescore
  32. 2026-08-12 13:48 UTCEPSS rescore
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  34. 2026-08-09 13:44 UTCEPSS rescore
  35. 2026-08-08 16:33 UTCEPSS rescore
  36. 2026-08-07 16:24 UTCEPSS rescore
  37. 2026-08-06 13:43 UTCEPSS rescore
  38. 2026-08-05 19:14 UTCEPSS rescore
  39. 2026-08-04 15:06 UTCEPSS rescore
  40. 2026-08-04 10:34 UTCEPSS rescore
  41. 2026-08-03 10:33 UTCEPSS rescore
  42. 2026-08-02 02:24 UTCEPSS rescore
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  44. 2026-08-01 04:13 UTCEPSS rescore
  45. 2026-07-30 16:25 UTCEPSS rescore
  46. 2026-07-30 01:28 UTCEPSS rescore
  47. 2026-07-28 15:33 UTCEPSS rescore
  48. 2026-07-26 14:52 UTCEPSS rescore
  49. 2026-07-26 14:52 UTCEPSS rescore
  50. 2026-07-25 14:15 UTCEPSS rescore
  51. 2026-07-24 14:15 UTCEPSS rescore
  52. 2026-07-23 14:16 UTCEPSS rescore
  53. 2026-07-23 14:16 UTCEPSS rescore
  54. 2026-07-23 02:03 UTCEG score recompute
  55. 2026-07-22 22:50 UTCEG score recompute
  56. 2026-07-22 14:06 UTCEPSS rescore
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  58. 2026-07-21 15:22 UTCEPSS rescore
  59. 2026-07-21 15:22 UTCEPSS rescore
  60. 2026-07-20 17:05 UTCEPSS rescore
  61. 2026-07-19 02:27 UTCEPSS rescore
  62. 2026-07-18 10:02 UTCEPSS rescore
  63. 2026-07-18 10:02 UTCEPSS rescore
  64. 2026-07-16 17:00 UTCEPSS rescore
  65. 2026-07-16 17:00 UTCEPSS rescore
  66. 2026-07-15 16:55 UTCEPSS rescore
  67. 2026-07-15 01:58 UTCEPSS rescore
  68. 2026-07-13 22:27 UTCEPSS rescore
  69. 2026-07-13 06:10 UTCEPSS rescore
  70. 2026-07-12 05:44 UTCEPSS rescore
  71. 2026-07-12 05:44 UTCEPSS rescore
  72. 2026-07-11 08:25 UTCEPSS rescore
  73. 2026-07-11 08:25 UTCEPSS rescore
  74. 2026-07-09 19:07 UTCEPSS rescore
  75. 2026-07-08 15:12 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-38543?
CVE-2021-38543 is a medium vulnerability published on August 11, 2021. TP-Link UE330 USB splitter devices 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…
When was CVE-2021-38543 disclosed?
CVE-2021-38543 was first published on August 11, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-38543 actively exploited?
CVE-2021-38543 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.3% probability of exploitation in the next 30 days (69th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-38543?
CVE-2021-38543 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2021-38543?
No fix for CVE-2021-38543 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix.

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