CVE-2021-1389

MEDIUMNVD 5.86.5▲
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.8; sources differ by 0.7.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1.2%CVSS: 5.8Exploit: None knownExposed services: Not assessed

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

A vulnerability in the IPv6 traffic processing of Cisco IOS XR Software and Cisco NX-OS Software for certain Cisco devices could allow an unauthenticated, remote attacker to bypass an IPv6 access control list (ACL) that is configured for an interface of an affected device. The vulnerability is due to improper processing of IPv6 traffic that is sent through an affected device. An attacker could exploit this vulnerability by sending crafted IPv6 packets that traverse the affected device. A successful exploit could allow the attacker to access resources that would typically be protected by the interface ACL.

CVSS v3
5.8
EG Score
6.5MEDIUMmedium confidence
EG Risk
45
EG Risk 45/100CISA 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
Severity65% × 45%
Exploitation1% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; 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
1.2%
EPSS %ILE
67th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; 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 (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). 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

February 4, 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 / 31× 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 170 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2021-1389?
CVE-2021-1389 is a medium vulnerability published on February 4, 2021. A vulnerability in the IPv6 traffic processing of Cisco IOS XR Software and Cisco NX-OS Software for certain Cisco devices could allow an unauthenticated, remote attacker to bypass an IPv6 access control list (ACL) that is configured for an interface of an affected device. The vulnerability is due…
When was CVE-2021-1389 disclosed?
CVE-2021-1389 was first published on February 4, 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-2021-1389 actively exploited?
CVE-2021-1389 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.2% probability of exploitation in the next 30 days (67th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-1389?
CVE-2021-1389 has a CVSS v3 base score of 5.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 6.5 (MEDIUM).
How do I remediate CVE-2021-1389?
No fix for CVE-2021-1389 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.

Dependency Blast Radius

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