CVE-2026-20171

MEDIUMNVD 6.86.8—
EchelonGraph scoreMEDIUM confidence

Score 6.8 from GitHub Security Advisory published 2026-05-20. NVD baseline CVSS 6.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.8Exploit: NoneExposed: 0

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

A vulnerability in the Border Gateway Protocol (BGP) enforce-first-as feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, remote attacker to trigger BGP peer flaps, resulting in a denial of service (DoS) condition. This vulnerability is due to incorrect parsing of a transitive BGP attribute. An attacker could exploit this vulnerability by sending a crafted BGP update through an established BGP peer session. If the update propagates to an affected device, it could cause the device to drop the BGP session and flap with the BGP peer that is forwarding this update, resulting in a DoS condition.

CVSS v3
6.8
EG Score
6.8(medium)
EPSS
37.2%
KEV
Not listed

Published

May 20, 2026

Last Modified

May 20, 2026

Advisory Details (1)

Auto-updated Jun 13, 2026
No patch confirmed yet.
generic

Cisco Nexus 3000 and 9000 Series Switches Border Gateway Protocol Denial of Service Vulnerability

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bgp-iefab-3hb2pwtx

Vendor Advisories for CVE-2026-20171(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 56× 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 120 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-20171?
CVE-2026-20171 is a medium vulnerability published on May 20, 2026. A vulnerability in the Border Gateway Protocol (BGP) enforce-first-as feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, remote attacker to trigger BGP peer flaps, resulting in a denial of service (DoS)…
When was CVE-2026-20171 disclosed?
CVE-2026-20171 was first published in the National Vulnerability Database on May 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20171 actively exploited?
CVE-2026-20171 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-20171?
CVE-2026-20171 has a CVSS v3 base score of 6.8 (NVD).
How do I remediate CVE-2026-20171?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20171, 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.

Dependency Blast Radius

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