CVE-2021-21820

Name: CVE-2021-21820
Creator: NVD / NIST
Published: 2021-07-16T11:15:10.037+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.96%

Last modified Jun 17, 2026

CVE-2021-21820 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 2.96% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

2.96%

85.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Dlink	Dir-3040 Firmware	1.13b03

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1285Exploit, Third Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1285Exploit, Third Party Advisory

Timeline

Published: Jul 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21820?

How severe is CVE-2021-21820?

CVE-2021-21820 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.96% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21820?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21820?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST