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Vulnerability record · CVE-2021-21820 · published 16 July 2021

CVE-2021-21820: Dlink dir-3040 firmware hard-coded credentials vulnerability

Dlink · Dir 3040 Firmware

A hard-coded password vulnerability exists in the Libcli Test Environment functionality of D-LINK DIR-3040 1.13B03. A specially crafted network request can lead to code execution. An attacker can send a sequence of requests to trigger this vulnerability.

9.8 CVSS 3.1 Critical EPSS 3.0% · top 13.3% CWE-798 · Hard-coded credentials
9.8CVSS 3.1 base score, v2 7.5
3.0%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

A hard-coded password vulnerability exists in the Libcli Test Environment functionality of D-LINK DIR-3040 1.13B03. A specially crafted network request can lead to code execution. An attacker can send a sequence of requests to trigger this vulnerability.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1285 ExploitThird Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1285 ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-44832Dlink dir-3040 firmware command injection vulnerabilityD-Link DIR-3040 device with firmware 120B03 was discovered to contain a command injection vulnerability via the SetTriggerLEDBlink function.EPSS 4.0%9.8CVE-2021-21913Dlink dir-3040 firmware hard-coded credentials vulnerabilityAn information disclosure vulnerability exists in the WiFi Smart Mesh functionality of D-LINK DIR-3040 1.13B03. A specially-crafted network request c…EPSS 2.2%8.8CVE-2023-41229Dlink dir-3040 firmware heap-based buffer overflow vulnerabilityD-Link DIR-3040 HTTP Request Processing Referer Heap-Based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adj…EPSS 1.0%8.8CVE-2023-41230Dlink dir-3040 firmware stack-based buffer overflow vulnerabilityD-Link DIR-3040 HTTP Request Processing Referer Stack-Based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-ad…EPSS 0.96%8.8CVE-2022-43648Dlink dir-3040 firmware heap-based buffer overflow vulnerabilityThis vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DIR-3040 1.20B03 routers. Authenti…EPSS 0.91%7.8CVE-2022-1262Dlink dir-1360 firmware os command injection vulnerabilityA command injection vulnerability in the protest binary allows an attacker with access to the remote command line interface to execute arbitrary comm…EPSS 2.2%7.5CVE-2021-21817Dlink dir-3040 firmware information exposure vulnerabilityAn information disclosure vulnerability exists in the Zebra IP Routing Manager functionality of D-LINK DIR-3040 1.13B03. A specially crafted network …EPSS 2.0%7.5CVE-2021-21818Dlink dir-3040 firmware hard-coded password vulnerabilityA hard-coded password vulnerability exists in the Zebra IP Routing Manager functionality of D-LINK DIR-3040 1.13B03. A specially crafted network requ…EPSS 1.7%

Source: NIST National Vulnerability Database (record CVE-2021-21820), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.