CVE-2021-20694Network attack vector

Authenticated Telnet activation via access-control bypass

Published Apr 26, 2021 · Updated Aug 3, 2024

Improper access control in D-Link DAP-1880AC firmware 1.21 and earlier allows remote authenticated users to start its Telnet service. Published material identifies the Telnet access-control path as the locus but does not disclose which request or check incorrectly enables the service. Valid low-privileged credentials and network reachability are required, and this CVE alone exposes Telnet rather than granting root access or code execution.

CVSS severity5.0
Medium
EPSS probability1.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in D-Link DAP-1880AC firmware 1.21 and earlier allows remote authenticated users to start its Telnet service. Published material identifies the Telnet access-control path as the locus but does not disclose which request or check incorrectly enables the service. Valid low-privileged credentials and network reachability are required, and this CVE alone exposes Telnet rather than granting root access or code execution.

The record

CVE
CVE-2021-20694
Published
Apr 26, 2021
Updated
Aug 3, 2024
Vendor
D-Link Corporation
Product
DAP-1880AC
Classifications
CWE-284, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 26, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=firmware version 1.21 and earlier

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

D-Link Corporation · DAP-1880ACversion=firmware version 1.21 and earlier

Published CVSS scores

5.0JPCERT/CCCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
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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