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CVE-2021-20776

31
FAUCET Score

CVE-2021-20776 describes a critical improper authentication vulnerability in A-Stage Inc.'s SCT-40CM01SR and AT-40CM01SR devices. This flaw allows an unauthenticated attacker to bypass access restrictions and execute arbitrary commands via Telnet, posing a severe risk to affected systems. With a CVSS score of 9.8 (Critical), the vulnerability is easily exploitable over the network with no user interaction or privileges required, leading to complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation, public exploit code, or KEV listing, the vulnerability has garnered significant community discussion, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:a-stage-inc:at-40cm01sr_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:a-stage-inc:sct-40cm01sr_firmware:-:*:*:*:*:*:*:*

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
1.29%
Probability of exploitation in next 30 days
EPSS Percentile
67.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0129 is in the 54th percentile among its peer group of 36,897 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

jvn.jp / en/jp/JVN21636825/index.html
Third Party Advisory