CVE-2021-20695Network attack vector

Root privilege escalation via undisclosed certificate-chain flaw

Published Apr 26, 2021 · Updated Aug 3, 2024

Improper certificate-chain validation in D-Link DAP-1880AC firmware 1.21 and earlier allows remote authenticated users to gain root privileges. D-Link has not disclosed which certificate-processing locus follows an untrusted chain incorrectly or how that operation yields elevation. Exploitation requires low-privileged remote access and grants a root shell on the appliance; no separate data impact has been published.

CVSS severity8.8
High
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate-chain validation in D-Link DAP-1880AC firmware 1.21 and earlier allows remote authenticated users to gain root privileges. D-Link has not disclosed which certificate-processing locus follows an untrusted chain incorrectly or how that operation yields elevation. Exploitation requires low-privileged remote access and grants a root shell on the appliance; no separate data impact has been published.

The record

CVE
CVE-2021-20695
Published
Apr 26, 2021
Updated
Aug 3, 2024
Vendor
D-Link Corporation
Product
DAP-1880AC
Classifications
CWE-296, T1068
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

8.8JPCERT/CCCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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-296Improper Following of a Certificate's Chain of Trust
T1068Exploitation for Privilege Escalation

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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