CVE-2021-1268

HIGHNVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.4 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 75% 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
7.4
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.4Exploit: NoneExposed: 0

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

A vulnerability in the IPv6 protocol handling of the management interfaces of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause an IPv6 flood on the management interface network of an affected device. The vulnerability exists because the software incorrectly forwards IPv6 packets that have an IPv6 node-local multicast group address destination and are received on the management interfaces. An attacker could exploit this vulnerability by connecting to the same network as the management interfaces and injecting IPv6 packets that have an IPv6 node-local multicast group address destination. A successful exploit could allow the attacker to cause an IPv6 flood on the corresponding network. Depending on the number of Cisco IOS XR Software nodes on that network segment, exploitation could cause excessive network traffic, resulting in network degradation or a denial of service (DoS) condition.

CVSS v3
7.4
EG Score
7.4(medium)
EPSS
40.0%
KEV
Not listed

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 8× in last 7d / 45× 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.

  1. 2026-07-22 14:05 UTCEPSS rescore
  2. 2026-07-21 15:22 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-20 17:04 UTCEPSS rescore
  5. 2026-07-19 14:28 UTCEPSS rescore
  6. 2026-07-19 02:26 UTCEPSS rescore
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  9. 2026-07-15 16:55 UTCEPSS rescore
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  11. 2026-07-15 01:57 UTCEPSS rescore
  12. 2026-07-13 22:27 UTCEPSS rescore
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  14. 2026-07-13 06:10 UTCEPSS rescore
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  16. 2026-07-12 05:44 UTCEPSS rescore
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  19. 2026-07-09 19:07 UTCEPSS rescore
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  21. 2026-07-07 13:43 UTCEPSS rescore
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  1. 2026-07-05 02:28 UTCEPSS rescore
  2. 2026-07-04 06:29 UTCEPSS rescore
  3. 2026-07-04 06:29 UTCEPSS rescore
  4. 2026-07-02 16:57 UTCEPSS rescore
  5. 2026-07-01 15:03 UTCEPSS rescore
  6. 2026-06-30 23:20 UTCEPSS rescore
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  8. 2026-06-29 14:04 UTCEPSS rescore
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  19. 2026-06-23 21:31 UTCEPSS rescore
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  21. 2026-06-22 14:24 UTCEPSS rescore
  22. 2026-06-22 14:23 UTCEPSS rescore
  23. 2026-06-21 14:54 UTCEPSS rescore
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  25. 2026-06-21 01:58 UTCEPSS rescore
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  27. 2026-06-19 19:24 UTCEPSS rescore
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  29. 2026-06-18 17:51 UTCEPSS rescore
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  35. 2026-06-13 22:58 UTCEPSS rescore
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  39. 2026-06-10 22:16 UTCEPSS rescore
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  42. 2026-06-08 14:15 UTCEPSS rescore
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  44. 2026-06-07 15:23 UTCEPSS rescore
  45. 2026-06-07 15:23 UTCEPSS rescore
  46. 2026-06-06 13:46 UTCEPSS rescore
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  49. 2026-06-05 22:45 UTCEPSS rescore
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  51. 2026-06-05 06:09 UTCEPSS rescore
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  54. 2026-06-04 13:10 UTCEPSS rescore
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  57. 2026-06-01 13:50 UTCEPSS rescore
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  59. 2026-05-31 22:29 UTCEPSS rescore
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  63. 2026-05-29 13:42 UTCEPSS rescore
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  66. 2026-05-27 13:39 UTCEPSS rescore
  67. 2026-05-26 21:20 UTCEG score recompute
  68. 2026-05-26 21:20 UTCGHSA enrichment
  69. 2026-05-26 13:42 UTCEPSS rescore
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  71. 2026-05-26 07:17 UTCEPSS rescore
  72. 2026-05-26 07:17 UTCEPSS rescore
  73. 2026-05-24 16:49 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-1268?
CVE-2021-1268 is a high vulnerability published on February 4, 2021. A vulnerability in the IPv6 protocol handling of the management interfaces of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause an IPv6 flood on the management interface network of an affected device. The vulnerability exists because the software incorrectly forwards…
When was CVE-2021-1268 disclosed?
CVE-2021-1268 was first published in the National Vulnerability Database 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-2021-1268 actively exploited?
CVE-2021-1268 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 40.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-1268?
CVE-2021-1268 has a CVSS v3 base score of 7.4 (NVD).
How do I remediate CVE-2021-1268?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1268, 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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