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CVE-2021-21805 (GCVE-0-2021-21805)

Vulnerability from cvelistv5 – Published: 2021-08-05 20:03 – Updated: 2024-08-03 18:23
VLAI Shadowserver Previdian
Summary
An OS Command Injection vulnerability exists in the ping.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). A specially crafted HTTP request can lead to arbitrary OS command execution. An attacker can send a crafted HTTP request to trigger this vulnerability.
Severity
9.8 (Critical)
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
  • CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Assigner
References
Impacted products
Vendor Product Version CPE status
n/a Advantech Affected: Advantech R-SeeNet 2.4.12 (20.10.2020)
Shadowserver
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 0375ab25-7c6a-47eb-beb4-63f93cfe42ed

Vulnerability ID: CVE-2021-21805

Status: Confirmed

Status Updated: 2026-07-20 00:00 UTC

Exploited: Yes

Characteristics
Severity: 98.0
Timestamps
First Seen: 2023-10-14
Asserted: 2023-10-14
Last Seen: 2026-07-20
Scope
Asset Exposure: ['internet-facing']
Notes: Affected: Advantech / R-SeeNet | Class: router | Severity: Critical (CVSS 9.8) | IoT: yes | In CISA KEV: no | Honeypot connections on 2026-07-20: 1
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 Advantech
30D Avg 0
90D Avg 2
Product R-SeeNet
Cisa Kev no
Connections 1
Observation Date 2026-07-20
Vulnerability Class CVSS
Vulnerability Score 9.8
Vulnerability Severity Critical
References
Created: 2026-06-30 09:23 UTC | Updated: 2026-07-22 01:00 UTC
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 8b40d2f0-45eb-447f-bcf2-f342df7b9dca

Vulnerability ID: CVE-2021-21805

Status: Confirmed

Status Updated: 2026-06-06 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2026-06-06
Asserted: 2026-06-06
Scope
Notes: KEVIntel entry: An OS Command Injection vulnerability exists in the ping.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). A specially crafted... | Affected: Advantech / R-SeeNet | CVSS: 9.8 (CRITICAL) | EPSS: 0.69631 | 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 OS Command Injection vulnerability exists in the ping.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). A specially crafted...
Vendor Advantech
Product R-SeeNet
Added Date 2026-06-06T00:00:00.000Z
Cvss Score 9.8
Epss Score 0.69631
Cvss Severity CRITICAL
Epss Percentile 0.99279
Used In Malware unknown
Ahead Of Cisa Kev None
Not Yet In Cisa Kev True
References
Created: 2026-06-23 14:03 UTC | Updated: 2026-07-10 06:14 UTC
Show details on NVD website
To clipboard 

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Tags
Taxonomy of the tags.





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

Author Source Type Date Other

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.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.