CVE-2021-20776

Unauthenticated command execution via Telnet login

Published Jul 7, 2021 · Updated Aug 3, 2024

Improper authentication in A-Stage SCT-40CM01SR and AT-40CM01SR televisions allows attackers to execute commands via Telnet. The devices' Telnet service accepts a login without authentication instead of enforcing its access restriction. Access to the device from an adjacent network is required; commands can affect the system, but product-function programs cannot be altered or deleted.

CVSS severity5.4
Medium
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in A-Stage SCT-40CM01SR and AT-40CM01SR televisions allows attackers to execute commands via Telnet. The devices' Telnet service accepts a login without authentication instead of enforcing its access restriction. Access to the device from an adjacent network is required; commands can affect the system, but product-function programs cannot be altered or deleted.

The record

CVE
CVE-2021-20776
Published
Jul 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-287, T1190
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.4JPCERT/CCCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
4.8JPCERT/CCAV:A/AC:L/Au:N/C:P/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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