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CVE-2021-20701

31
FAUCET Score

CVE-2021-20701 is a critical buffer overflow vulnerability affecting NEC CLUSTERPRO X and EXPRESSCLUSTER X products for Windows, including their SingleServerSafe variants, version 4.3 and earlier. This flaw allows an unauthenticated attacker to achieve remote code execution over the network with low attack complexity. With a CVSS score of 9.8, the potential impact is severe, leading to complete compromise of confidentiality, integrity, and availability. While the vulnerability is critical, there is currently no public exploit code available, no evidence of active exploitation, and minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.0, <= 4.3CPE matchmatch criteria
cpe:2.3:a:nec:clusterpro_x:*:*:*:*:*:windows:*:*
>= 1.0, <= 4.3CPE matchmatch criteria
cpe:2.3:a:nec:clusterpro_x_singleserversafe:*:*:*:*:*:windows:*:*
>= 1.0, <= 4.3CPE matchmatch criteria
cpe:2.3:a:nec:expresscluster_x:*:*:*:*:*:windows:*:*
>= 1.0, <= 4.3CPE matchmatch criteria
cpe:2.3:a:nec:expresscluster_x_singleserversafe:*:*:*:*:*:windows:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.07%
Probability of exploitation in next 30 days
EPSS Percentile
79.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0207 is in the 68th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

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