CVE-2021-42071Public exploitNetwork attack vector

Unauthenticated command execution via User-Agent shell injection

Published Oct 7, 2021 · Updated Aug 4, 2024

OS command injection in Visual Tools DVR VX16 4.2.28.0 allows remote attackers to execute arbitrary commands through unauthenticated HTTP requests. The cgi-bin/slogin/login.py CGI exposes the User-Agent header to Bash without neutralizing shell metacharacters, causing appended commands to run. No credentials or user interaction are required, and commands execute as an unprivileged Linux account within that account's permissions.

CVSS severity9.8
Critical
EPSS probability69.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Visual Tools DVR VX16 4.2.28.0 allows remote attackers to execute arbitrary commands through unauthenticated HTTP requests. The cgi-bin/slogin/login.py CGI exposes the User-Agent header to Bash without neutralizing shell metacharacters, causing appended commands to run. No credentials or user interaction are required, and commands execute as an unprivileged Linux account within that account's permissions.

The record

CVE
CVE-2021-42071
Published
Oct 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, T1059.004, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Unix Shell
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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