CVE-2021-20716

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 3.2%, top 13% of all CVEs by exploit prediction. 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
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 3%CVSS: 9.8Exploit: None knownExposed: 0

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

Hidden functionality in multiple Buffalo network devices (BHR-4RV firmware Ver.2.55 and prior, FS-G54 firmware Ver.2.04 and prior, WBR2-B11 firmware Ver.2.32 and prior, WBR2-G54 firmware Ver.2.32 and prior, WBR2-G54-KD firmware Ver.2.32 and prior, WBR-B11 firmware Ver.2.23 and prior, WBR-G54 firmware Ver.2.23 and prior, WBR-G54L firmware Ver.2.20 and prior, WHR2-A54G54 firmware Ver.2.25 and prior, WHR2-G54 firmware Ver.2.23 and prior, WHR2-G54V firmware Ver.2.55 and prior, WHR3-AG54 firmware Ver.2.23 and prior, WHR-G54 firmware Ver.2.16 and prior, WHR-G54-NF firmware Ver.2.10 and prior, WLA2-G54 firmware Ver.2.24 and prior, WLA2-G54C firmware Ver.2.24 and prior, WLA-B11 firmware Ver.2.20 and prior, WLA-G54 firmware Ver.2.20 and prior, WLA-G54C firmware Ver.2.20 and prior, WLAH-A54G54 firmware Ver.2.54 and prior, WLAH-AM54G54 firmware Ver.2.54 and prior, WLAH-G54 firmware Ver.2.54 and prior, WLI2-TX1-AG54 firmware Ver.2.53 and prior, WLI2-TX1-AMG54 firmware Ver.2.53 and prior, WLI2-TX1-G54 firmware Ver.2.20 and prior, WLI3-TX1-AMG54 firmware Ver.2.53 and prior, WLI3-TX1-G54 firmware Ver.2.53 and prior, WLI-T1-B11 firmware Ver.2.20 and prior, WLI-TX1-G54 firmware Ver.2.20 and prior, WVR-G54-NF firmware Ver.2.02 and prior, WZR-G108 firmware Ver.2.41 and prior, WZR-G54 firmware Ver.2.41 and prior, WZR-HP-G54 firmware Ver.2.41 and prior, WZR-RS-G54 firmware Ver.2.55 and prior, and WZR-RS-G54HP firmware Ver.2.55 and prior) allows a remote attacker to enable the debug option and to execute arbitrary code or OS commands, change the configuration, and cause a denial of service (DoS) condition.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

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
Severity98% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
3%
EPSS %ILE
87%
KEV
Not listed

Published

April 28, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Aug 15, 2026
No patch confirmed yet.
generic
https://www.buffalo.jp/news/detail/20210427-02.html
generic

JVNVU#90274525: Multiple Buffalo network devices contain hidden functionality

https://jvn.jp/en/vu/JVNVU90274525/index.html

Data Freshness Timeline

(refreshed 7× in last 7d / 29× 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 122 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2021-20716?
CVE-2021-20716 is a critical vulnerability published on April 28, 2021. Hidden functionality in multiple Buffalo network devices (BHR-4RV firmware Ver.2.55 and prior, FS-G54 firmware Ver.2.04 and prior, WBR2-B11 firmware Ver.2.32 and prior, WBR2-G54 firmware Ver.2.32 and prior, WBR2-G54-KD firmware Ver.2.32 and prior, WBR-B11 firmware Ver.2.23 and prior, WBR-G54…
When was CVE-2021-20716 disclosed?
CVE-2021-20716 was first published in the National Vulnerability Database on April 28, 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-2021-20716 actively exploited?
CVE-2021-20716 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3% probability of exploitation in the next 30 days, which ranks it in the top 13.0% of all scored CVEs.
What is the CVSS score of CVE-2021-20716?
CVE-2021-20716 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-20716?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-20716, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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