No exploitation reportedFix available

CVE-2021-20740

Q: Is CVE-2021-20740 actively exploited?

Active exploitation of CVE-2021-20740 has not been confirmed. Its EPSS score was 3.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-20740?

CVE-2021-20740 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-06-28
Fixed in6.4.3-09 · 5.5.3-09
WeaknessCWE-78

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Hitachi Virtual File Platform Versions prior to 5.5.3-09 and Versions prior to 6.4.3-09, and NEC Storage M Series NAS Gateway Nh4a/Nh8a versions prior to FOS 5.5.3-08(NEC2.5.4a) and Nh4b/Nh8b, Nh4c/Nh8c versions prior to FOS 6.4.3-08(NEC3.4.2) allow remote authenticated attackers to execute arbitrary OS commands with root privileges via unspecified vectors.

Timeline

dates in UTC

2021-06-2801:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-20740?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-20740?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Hitachi virtual file platform

Branch	Affected	Fixed in	Source
6.4	< 6.4.3-09	6.4.3-09	NVD
5.5	< 5.5.3-09	5.5.3-09	NVD

Nec nas gateway nh4a firmwareversion to verify

Branch	Affected	Fixed in	Source
—	< fos_5.5.3-08\(nec2.5.4a\)	fos_5.5.3-08\(nec2.5.4a\)	NVD

Nec nas gateway nh4b firmwareversion to verify

Branch	Affected	Fixed in	Source
—	< fos_6.4.3-08\(nec3.4.2\)	fos_6.4.3-08\(nec3.4.2\)	NVD

4 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Hitachi virtual file platform to 6.4.3-09 · 5.5.3-09

Advisories and patches

jpn.nec.comVendor Advisory
www.hitachi.co.jpVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.09read 2026-10-23
NVDweakness (CWE)CWE-78read 2026-10-23
FIRST EPSSEPSS score3.1 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published: 2021-06-28
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-20740?

Is CVE-2021-20740 actively exploited?

Active exploitation of CVE-2021-20740 has not been confirmed. Its EPSS score was 3.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-20740?

CVE-2021-20740 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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