How severe is CVE-2021-20702?

CVE-2021-20702 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20702 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20702?

CVE-2021-20702 primarily affects Nec Clusterpro X. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20702?

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

When was CVE-2021-20702 published?

CVE-2021-20702 was published on 2021-11-03 and last updated on 2026-06-17.

CVE-2021-20702

CVE-2021-20702 is a critical-severity vulnerability in Nec Clusterpro X with a CVSS 3.x base score of 9.8. 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-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (80th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Nec Clusterpro X
Published: 2021-11-03
Last modified: 2026-06-17

Description

Buffer overflow vulnerability in the Transaction Server CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X 4.3 for Windows and earlier, CLUSTERPRO X 4.3 SingleServerSafe for Windows and earlier, EXPRESSCLUSTER X 4.3 SingleServerSafe for Windows and earlier allows attacker to remote code execution via a network.

Frequently asked questions

What is CVE-2021-20702?: Buffer overflow vulnerability in the Transaction Server CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X 4.3 for Windows and earlier, CLUSTERPRO X 4.3 SingleServerSafe for Windows and earlier, EXPRESSCLUSTER X 4.3 SingleServerSafe for Windows and earlier allows attacker to remote code execution via a network.
How severe is CVE-2021-20702?: CVE-2021-20702 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20702 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20702?: CVE-2021-20702 primarily affects Nec Clusterpro X. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20702?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-20702 published?: CVE-2021-20702 was published on 2021-11-03 and last updated on 2026-06-17.

References

https://jpn.nec.com/security-info/secinfo/nv21-015_en.html

Affected products (4)

cpe:2.3:a:nec:clusterpro_x:*:*:*:*:*:windows:*:*
cpe:2.3:a:nec:clusterpro_x_singleserversafe:*:*:*:*:*:windows:*:*
cpe:2.3:a:nec:expresscluster_x:*:*:*:*:*:windows:*:*
cpe:2.3:a:nec:expresscluster_x_singleserversafe:*:*:*:*:*:windows:*:*

More vulnerabilities in Nec Clusterpro X

CVE-2021-20704 — Critical (CVSS 9.8): Buffer overflow vulnerability in the compatible API with previous versions CLUSTERPRO X 4.3 for Windows and earlier,…
CVE-2021-20703 — Critical (CVSS 9.8): Buffer overflow vulnerability in the Transaction Server CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X 4.3…
CVE-2021-20701 — Critical (CVSS 9.8): Buffer overflow vulnerability in the Disk Agent CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X 4.3 for…
CVE-2021-20700 — Critical (CVSS 9.8): Buffer overflow vulnerability in the Disk Agent CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X 4.3 for…
CVE-2021-20707 — High (CVSS 7.5): Improper input validation vulnerability in the Transaction Server CLUSTERPRO X 4.3 for Windows and earlier,…
CVE-2021-20706 — High (CVSS 7.5): Improper input validation vulnerability in the WebManager CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X…

All CVEs affecting Nec Clusterpro X →

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