CVE-2021-1377

MEDIUMNVD 5.85.8—
EchelonGraph scoreMEDIUM confidence

Score 5.8 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.8Exploit: NoneExposed: 0

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

A vulnerability in Address Resolution Protocol (ARP) management of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent an affected device from resolving ARP entries for legitimate hosts on the connected subnets. This vulnerability exists because ARP entries are mismanaged. An attacker could exploit this vulnerability by continuously sending traffic that results in incomplete ARP entries. A successful exploit could allow the attacker to cause ARP requests on the device to be unsuccessful for legitimate hosts, resulting in a denial of service (DoS) condition.

CVSS v3
5.8
EG Score
5.8(medium)
EG Risk
—
EPSS
70.3%
KEV
Not listed

Published

March 24, 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 9× in last 7d / 46× 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 22:42 UTCEG score recompute
  2. 2026-07-22 14:05 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
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  67. 2026-05-27 13:39 UTCEPSS rescore
  68. 2026-05-26 19:27 UTCEG score recompute
  69. 2026-05-26 19:27 UTCGHSA enrichment
  70. 2026-05-26 13:42 UTCEPSS rescore
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  72. 2026-05-26 07:17 UTCEPSS rescore
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  74. 2026-05-24 16:49 UTCEPSS rescore
  75. 2026-05-23 10:31 UTCOSV refresh

Frequently asked(5)

What is CVE-2021-1377?
CVE-2021-1377 is a medium vulnerability published on March 24, 2021. A vulnerability in Address Resolution Protocol (ARP) management of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent an affected device from resolving ARP entries for legitimate hosts on the connected subnets. This vulnerability exists because…
When was CVE-2021-1377 disclosed?
CVE-2021-1377 was first published in the National Vulnerability Database on March 24, 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-2021-1377 actively exploited?
CVE-2021-1377 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 70.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-1377?
CVE-2021-1377 has a CVSS v3 base score of 5.8 (NVD).
How do I remediate CVE-2021-1377?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1377, 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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