How severe is CVE-2021-40334?

CVE-2021-40334 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-40334 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40334?

CVE-2021-40334 primarily affects Hitachienergy Fox615 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-40334?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-40334 published?

CVE-2021-40334 was published on 2021-12-02 and last updated on 2026-06-17.

CVE-2021-40334

CVE-2021-40334 is a high-severity vulnerability in Hitachienergy Fox615 Firmware with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-431.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 5.0
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-431
Affected product: Hitachienergy Fox615 Firmware
Published: 2021-12-02
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-40334?: 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.
How severe is CVE-2021-40334?: CVE-2021-40334 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-40334 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40334?: CVE-2021-40334 primarily affects Hitachienergy Fox615 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-40334?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-40334 published?: CVE-2021-40334 was published on 2021-12-02 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:hitachienergy:fox615_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:hitachienergy:xcm20_firmware:*:*:*:*:*:*:*:*

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