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NVD / CVE Program· CNA talos

CVE-2021-21913: An information disclosure vulnerability exists in the WiFi Smart Mesh functionality of D-LINK DIR-3040 1.13B03.

CriticalCVSS 9.8 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Plan (action score 40/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.1% (FIRST EPSS); higher than 82.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Add it to your regular patch cycle. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An information disclosure vulnerability exists in the WiFi Smart Mesh functionality of D-LINK DIR-3040 1.13B03. A specially-crafted network request can lead to command execution. An attacker can connect to the MQTT service to trigger this vulnerability.

Published
Sep 23, 2021
Updated
Jun 16, 2026
EPSS
2.1% · 82th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.1%

CNA vs NVD score

NVD
9.8
CNA · talos
10.0
0.2 point gap

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-21913

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
dlinkdir-3040 firmware
dlinkdir-3040

Versions reported by the vendor

Affected version ranges reported by the assigning authority (talos). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a D-Link

    • D-LINK DIR-3040 1.13B03affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • dlink dir-3040 firmware1.13b03

Same product

dlink: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-44832D-Link DIR-3040 device with firmware 120B03 was discovered to contain a command injection vulnerability via the SetTriggerLEDBlink function.
    40Plan
  • CVE-2021-21820A hard-coded password vulnerability exists in the Libcli Test Environment functionality of D-LINK DIR-3040 1.13B03.
    40Plan
  • CVE-2023-41230D-Link DIR-3040 HTTP Request Processing Referer Stack-Based Buffer Overflow Remote Code Execution Vulnerability
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-21818Jul 16, 2021 · A hard-coded password vulnerability exists in the Zebra IP Routing Manager functionality of D-LINK DIR-3040 1.13B03.
    31Monitor
  • ← EarlierCVE-2021-21819Jul 16, 2021 · A code execution vulnerability exists in the Libcli Test Environment functionality of D-LINK DIR-3040 1.13B03.
    29Monitor
  • Later →CVE-2022-43648Mar 29, 2023 · This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DIR-3040 1.20B03 routers.
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-798 · Use of Hard-coded Credentials

CVSS vector

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

nvd-primary

Root cause

For convenience in support or manufacturing, an account that is identical on every device is embedded in the software. Credentials learned from one device work on all of them.

The bug in code

The whole CWE-798 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const SUPPORT_USER = "support";const SUPPORT_PASS = "hardcoded-password";

Fixed

ts
const creds = await provisioning.deviceCredentials(deviceId);if (creds.mustRotate) await forcePasswordChange(deviceId);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

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