CVE-2021-1521

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 67% 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
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

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

A vulnerability in the Cisco Discovery Protocol implementation for Cisco Video Surveillance 8000 Series IP Cameras could allow an unauthenticated, adjacent attacker to cause an affected IP camera to reload. This vulnerability is due to missing checks when processing Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected IP camera. A successful exploit could allow the attacker to cause the affected IP camera to reload unexpectedly, resulting in a denial of service (DoS) condition. Note: Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

May 6, 2021

Last Modified

November 21, 2024

References (2)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 30× 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 127 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
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  10. 2026-08-11 13:38 UTCEPSS rescore
  11. 2026-08-09 13:43 UTCEPSS rescore
  12. 2026-08-08 16:33 UTCEPSS rescore
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  15. 2026-08-05 19:14 UTCEPSS rescore
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  17. 2026-08-04 10:34 UTCEPSS rescore
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  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
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  24. 2026-07-26 14:52 UTCEPSS rescore
  25. 2026-07-25 14:15 UTCEPSS rescore
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  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 22:42 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
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  15. 2026-07-15 01:57 UTCEPSS rescore
  16. 2026-07-13 22:27 UTCEPSS rescore
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  18. 2026-07-13 06:10 UTCEPSS rescore
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  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
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  31. 2026-07-04 06:29 UTCEPSS rescore
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  33. 2026-07-02 16:57 UTCEPSS rescore
  34. 2026-07-01 15:03 UTCEPSS rescore
  35. 2026-06-30 23:20 UTCEPSS rescore
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  37. 2026-06-29 14:04 UTCEPSS rescore
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  39. 2026-06-28 14:05 UTCEPSS rescore
  40. 2026-06-28 04:54 UTCEPSS rescore
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  42. 2026-06-27 03:06 UTCEPSS rescore
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  44. 2026-06-25 13:48 UTCEPSS rescore
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  46. 2026-06-24 14:03 UTCEPSS rescore
  47. 2026-06-24 14:03 UTCEPSS rescore
  48. 2026-06-23 21:31 UTCEPSS rescore
  49. 2026-06-23 21:31 UTCEPSS rescore
  50. 2026-06-22 14:24 UTCEPSS rescore
  51. 2026-06-22 14:23 UTCEPSS rescore
  52. 2026-06-21 14:54 UTCEPSS rescore
  53. 2026-06-21 14:54 UTCEPSS rescore
  54. 2026-06-21 01:58 UTCEPSS rescore
  55. 2026-06-21 01:57 UTCEPSS rescore
  56. 2026-06-19 19:24 UTCEPSS rescore
  57. 2026-06-19 19:24 UTCEPSS rescore
  58. 2026-06-18 17:51 UTCEPSS rescore
  59. 2026-06-18 17:51 UTCEPSS rescore
  60. 2026-06-17 17:51 UTCEPSS rescore
  61. 2026-06-16 17:50 UTCEPSS rescore
  62. 2026-06-15 17:46 UTCEPSS rescore
  63. 2026-06-14 23:15 UTCEPSS rescore
  64. 2026-06-13 22:58 UTCEPSS rescore
  65. 2026-06-12 23:10 UTCEPSS rescore
  66. 2026-06-12 23:10 UTCEPSS rescore
  67. 2026-06-11 13:58 UTCEPSS rescore
  68. 2026-06-10 22:16 UTCEPSS rescore
  69. 2026-06-10 22:16 UTCEPSS rescore
  70. 2026-06-10 13:20 UTCEPSS rescore
  71. 2026-06-08 14:15 UTCEPSS rescore
  72. 2026-06-08 14:15 UTCEPSS rescore
  73. 2026-06-07 15:23 UTCEPSS rescore
  74. 2026-06-07 15:23 UTCEPSS rescore
  75. 2026-06-06 13:46 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-1521?
CVE-2021-1521 is a medium vulnerability published on May 6, 2021. A vulnerability in the Cisco Discovery Protocol implementation for Cisco Video Surveillance 8000 Series IP Cameras could allow an unauthenticated, adjacent attacker to cause an affected IP camera to reload. This vulnerability is due to missing checks when processing Cisco Discovery Protocol…
When was CVE-2021-1521 disclosed?
CVE-2021-1521 was first published in the National Vulnerability Database on May 6, 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-2021-1521 actively exploited?
CVE-2021-1521 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.1% of all scored CVEs.
What is the CVSS score of CVE-2021-1521?
CVE-2021-1521 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2021-1521?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1521, 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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