CVE-2021-1230

HIGHNVD 8.68.6
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This high-severity CVE scores 8.6 under NVD CVSS v3. EPSS exploit probability: 1.5% (74th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Trending — 3 sources updated this week
8.6EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.5%CVSS: 8.6Exploit: None knownExposed services: Not assessed

No fix has been recorded since the CVE record was published in 2021 — use a compensating control (WAF / firewall / segmentation) and check the vendor's advisory.

A vulnerability with the Border Gateway Protocol (BGP) for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a routing process to crash, which could lead to a denial of service (DoS) condition. This vulnerability is due to an issue with the installation of routes upon receipt of a BGP update. An attacker could exploit this vulnerability by sending a crafted BGP update to an affected device. A successful exploit could allow the attacker to cause the routing process to crash, which could cause the device to reload. This vulnerability applies to both Internal BGP (IBGP) and External BGP (EBGP). Note: The Cisco implementation of BGP accepts incoming BGP traffic from explicitly configured peers only. To exploit this vulnerability, an attacker would need to send a specific BGP update message over an established TCP connection that appears to come from a trusted BGP peer.

CVSS v3
8.6
EG Score
8.6HIGHmedium confidence
EG Risk
54
EG Risk 54/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity86% × 45%
Impact severity (EG Severity): CVSS 8.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation1.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix has been recorded since the CVE record was published in 2021. 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 check the vendor's advisory for a fix.
EPSS PROB
1.5%
EPSS %ILE
74th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (8.6): severity, escalated by confirmed exploitation. This CVE's 8.6 is its impact severity (EG Severity), not escalated.

EG Severity
8.6 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
1.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-20). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

No fix has been recorded since the CVE record was published in 2021. 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 check the vendor's advisory for a fix.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

February 24, 2021

Last Modified

November 21, 2024

Advisory Details (1)

Auto-updated Sep 1, 2026
No fix on record since 2021.
Web page

Cisco Nexus 9000 Series Fabric Switches ACI Mode BGP Route Installation Denial of Service Vulnerability

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n9kaci-bgp-De9dPKSK

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 35× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 94 of 191 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 6 repeat rows among the latest 100 are merged into the row they repeat. The 97 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-23 16:28 UTCEPSS rescoreEPSS 1.5% · 74th percentile
  2. 2026-10-22 16:29 UTCEPSS rescoreEPSS 1.5% · 74th percentile
  3. 2026-10-21 16:28 UTCEPSS rescoreEPSS 1.5% · 74th percentile
  4. 2026-10-21 11:07 UTCEG score recompute
  5. 2026-10-21 11:07 UTCGHSA enrichmentGHSA-5hv8-h736-6fwx · GitHub severity HIGH
  6. 2026-10-20 16:28 UTCEPSS rescoreEPSS 1.5% · 74th percentile
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  8. 2026-10-18 16:28 UTCEPSS rescoreEPSS 1.5% · 74th percentile
  9. 2026-10-18 09:14 UTCEG score recompute
  10. 2026-10-17 16:28 UTCEPSS rescoreEPSS 1.5% · 74th percentile
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  15. 2026-10-12 19:27 UTCEG score recompute
  16. 2026-10-12 16:29 UTCEPSS rescoreEPSS 1.5% · 74th percentile
  17. 2026-10-11 23:52 UTCEG score recompute
  18. 2026-10-11 13:43 UTCEPSS rescoreEPSS 1.5% · 74th percentile
  19. 2026-10-10 19:56 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
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  1. 2026-10-03 14:22 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
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  3. 2026-10-01 19:46 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  4. 2026-09-30 15:27 UTCEG score recompute
  5. 2026-09-30 15:00 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  6. 2026-09-28 13:47 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
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  8. 2026-09-26 15:54 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
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  14. 2026-09-19 15:37 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
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  66. 2026-07-23 01:56 UTCEG score recompute
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  68. 2026-07-22 14:05 UTCEPSS rescoreEPSS 1.5% · 71st percentile
  69. 2026-07-21 15:22 UTCEPSS rescoreEPSS 1.5% · 71st percentile

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Frequently asked(5)

What is CVE-2021-1230?
CVE-2021-1230 is a high-severity vulnerability; its CVE record was published on February 24, 2021. A vulnerability with the Border Gateway Protocol (BGP) for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a routing process to crash, which could lead to a denial of service (DoS) condition. This…
When was CVE-2021-1230 made public?
CVE-2021-1230 was made public on February 24, 2021: that is the date its CVE record's CNA, Cisco Systems, Inc., gives for when the vulnerability was made public. The CVE record itself was published on February 24, 2021. EchelonGraph's copy of the record carries a last-modified date of November 21, 2024; the record at its source may have been updated since.
Is CVE-2021-1230 actively exploited?
CVE-2021-1230 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.5% probability of exploitation in the next 30 days (74th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-1230?
CVE-2021-1230 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2021-1230?
No fix for CVE-2021-1230 has been recorded since its CVE record was published in 2021. 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 check the vendor's advisory for a fix.

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