CVE-2021-39509 (GCVE-0-2021-39509)

Vulnerability from cvelistv5 – Published: 2021-08-24 18:52 – Updated: 2024-08-04 02:06
VLAI Shadowserver Previdian
Summary
An issue was discovered in D-Link DIR-816 DIR-816A2_FWv1.10CNB05_R1B011D88210 The HTTP request parameter is used in the handler function of /goform/form2userconfig.cgi route, which can construct the user name string to delete the user function. This can lead to command injection through shell metacharacters.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
  • n/a
Assigner
References
Shadowserver
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 51bceadc-eed1-4cdf-869b-10fc674a6cba

Vulnerability ID: CVE-2021-39509

Status: Confirmed

Status Updated: 2024-10-09 03:25 UTC

Exploited: Yes

Characteristics
Severity: 98.0
Timestamps
First Seen: 2024-10-09
Asserted: 2024-10-09
Last Seen: 2024-10-09
Scope
Asset Exposure: ['internet-facing']
Notes: Affected: D-Link / D-Link DIR-816/DIR-816A2 | Class: router | Severity: Critical (CVSS 9.8) | IoT: yes | In CISA KEV: no | Honeypot connections on 2024-10-09: 81
Evidence

Type: Honeypot

Signal: In The Wild Attempts

Confidence: 70%

Source: shadowserver

Details
1D 1
Iot yes
Feed Shadowserver Foundation honeypot/exploited-vulnerabilities
Type http-scan
Class router
7D Avg 0
Vendor D-Link
30D Avg 0
90D Avg 0
Product D-Link DIR-816/DIR-816A2
Cisa Kev no
Connections 81
Observation Date 2024-10-09
Vulnerability Class CVSS
Vulnerability Score 9.8
Vulnerability Severity Critical
References
Created: 2026-06-30 12:19 UTC | Updated: 2026-06-30 12:19 UTC
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: eebbb5b3-1e7e-4a0c-a700-57c26308a5a3

Vulnerability ID: CVE-2021-39509

Status: Confirmed

Status Updated: 2021-08-24 18:52 UTC

Exploited: Yes

Timestamps
First Seen: 2021-08-24
Asserted: 2021-08-24
Scope
Notes: KEVIntel entry: An issue was discovered in D-Link DIR-816 DIR-816A2_FWv1.10CNB05_R1B011D88210 The HTTP request parameter is used in the handler function of... | Affected: n/a / n/a | Used in malware: unknown | Not yet in CISA KEV: True
Evidence

Type: Public Report

Signal: Successful Exploitation

Confidence: 70%

Source: kevintel

Details
Feed KEVIntel (kevintel.com)
Title An issue was discovered in D-Link DIR-816 DIR-816A2_FWv1.10CNB05_R1B011D88210 The HTTP request parameter is used in the handler function of...
Vendor n/a
Product n/a
Added Date 2021-08-24T18:52:26.000Z
Cvss Score None
Epss Score None
Cvss Severity None
Epss Percentile None
Used In Malware unknown
Ahead Of Cisa Kev None
Not Yet In Cisa Kev True
References
Created: 2026-06-23 14:06 UTC | Updated: 2026-07-10 06:14 UTC
Show details on NVD website
To clipboard 

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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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