CVE-2021-40334

HIGHNVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.6 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 39% 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
8.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 8.6Exploit: NoneExposed: 0

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

Missing Handler vulnerability in the proprietary management protocol (port TCP 5558) of Hitachi Energy FOX61x, XCM20 allows an attacker that exploits the vulnerability by activating SSH on port TCP 5558 to cause disruption to the NMS and NE communication. This issue affects: Hitachi Energy FOX61x versions prior to R15A. Hitachi Energy XCM20 versions prior to R15A.

CVSS v3
8.6
EG Score
8.6(medium)
EPSS
57.8%
KEV
Not listed

Published

December 2, 2021

Last Modified

November 21, 2024

References (4)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× 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.

Showing the most recent 100 of 102 total refreshes for this CVE.

  1. 2026-07-22 14:06 UTCEPSS rescore
  2. 2026-07-21 15:22 UTCEPSS rescore
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  1. 2026-07-06 02:21 UTCEPSS rescore
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  24. 2026-06-21 01:58 UTCEPSS rescore
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  26. 2026-06-19 19:24 UTCEPSS rescore
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  43. 2026-06-10 22:16 UTCEPSS rescore
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  48. 2026-06-07 15:23 UTCEPSS rescore
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  50. 2026-06-06 13:46 UTCEPSS rescore
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  52. 2026-06-05 22:45 UTCEPSS rescore
  53. 2026-06-05 06:09 UTCEPSS rescore
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  75. 2026-05-26 06:57 UTCEG score recompute

Frequently asked(5)

What is CVE-2021-40334?
CVE-2021-40334 is a high vulnerability published on December 2, 2021. Missing Handler vulnerability in the proprietary management protocol (port TCP 5558) of Hitachi Energy FOX61x, XCM20 allows an attacker that exploits the vulnerability by activating SSH on port TCP 5558 to cause disruption to the NMS and NE communication. This issue affects: Hitachi Energy FOX61x…
When was CVE-2021-40334 disclosed?
CVE-2021-40334 was first published in the National Vulnerability Database on December 2, 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-2021-40334 actively exploited?
CVE-2021-40334 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 57.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-40334?
CVE-2021-40334 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2021-40334?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40334, 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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