CVE-2021-1394

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.3Exploit: NoneExposed: 0

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

A vulnerability in the ingress traffic manager of Cisco IOS XE Software for Cisco Network Convergence System (NCS) 520 Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the web management interface of an affected device. This vulnerability is due to incorrect processing of certain IPv4 TCP traffic that is destined to an affected device. An attacker could exploit this vulnerability by sending a large number of crafted TCP packets to the affected device. A successful exploit could allow the attacker to cause the web management interface to become unavailable, resulting in a DoS condition. Note: This vulnerability does not impact traffic that is going through the device or going to the Management Ethernet interface of the device.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
—
EPSS
66.8%
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 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 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. 2026-05-26 19:27 UTCGHSA enrichment
  68. 2026-05-26 13:42 UTCEPSS rescore
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  72. 2026-05-24 16:49 UTCEPSS rescore
  73. 2026-05-23 10:31 UTCOSV refresh

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Frequently asked(5)

What is CVE-2021-1394?
CVE-2021-1394 is a medium vulnerability published on March 24, 2021. A vulnerability in the ingress traffic manager of Cisco IOS XE Software for Cisco Network Convergence System (NCS) 520 Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the web management interface of an affected device. This vulnerability is…
When was CVE-2021-1394 disclosed?
CVE-2021-1394 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-2021-1394 actively exploited?
CVE-2021-1394 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 66.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-1394?
CVE-2021-1394 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2021-1394?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1394, 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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