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Vulnerabilities

Vulnerability · CVE-2021-4473

topsecgroup tianxin_internet_behavior_management_system Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Published Apr 6, 2026 · catalog updated Jun 17, 2026 · Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System

Patch now

CVE-2021-4473 is in the CISA known-exploited catalog. Confirm Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Critical9.3
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
6.17%
Remediation
Remediation guidance
Affected products
cpe topsecgroup/tianxin internet behavior management system · vendor Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System

Tianxin Internet Behavior Management System contains a command injection vulnerability in the Reporter component endpoint that allows unauthenticated attackers to execute arbitrary commands by supplying a crafted objClass parameter containing shell metacharacters and output redirection. Attackers can exploit this vulnerability to write malicious PHP files into the web root and achieve remote code execution with the privileges of the web server process. This vulnerability has been fixed in version NACFirmware_4.0.0.7_20210716.180815_topsec_0_basic.bin. Exploitation evidence was first observed by the Shadowserver Foundation on 2024-06-01 (UTC).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe topsecgroup/tianxin internet behavior management systemversion unspecified
  • vendor Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management Systemversion unspecified

How to fix CVE-2021-4473

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-4473 is in the CISA known-exploited catalog. Confirm Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

CWE-78: OS Command Injection. EPSS 6.17%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 6, 2026 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

  2. Apr 7, 2026 · NIST NVD

    Detected

    Tianxin Internet Behavior Management System contains a command injection vulnerability in the Reporter component endpoint that allows unauthenticated attackers to execute arbitrary commands by supplying a crafted objClass parameter containing shell metacharacters and output redirection. Attackers can exploit this vulnerability to write malicious PHP files into the web root and achieve remote code

  3. Jun 17, 2026 · NIST NVD

    Updated

    Tianxin Internet Behavior Management System contains a command injection vulnerability in the Reporter component endpoint that allows unauthenticated attackers to execute arbitrary commands by supplying a crafted objClass parameter containing shell metacharacters and output redirection. Attackers can exploit this vulnerability to write malicious PHP files into the web root and achieve remote code

Sources

  • CVE.orgVulnerability recordCVE-2021-4473

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-4473

    30-day exploitation probability 6.2%

    first.org
  • NIST NVDVulnerability recordCVE-2021-4473

    Tianxin Internet Behavior Management System contains a command injection vulnerability in the Reporter component endpoint that allows unauthenticated attackers to execute arbitrary commands by supplying a crafted objClass parameter containing shell metacharacters and output redir

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2021-4473

    Tianxin Internet Behavior Management System contains a command injection vulnerability in the Reporter component endpoint that allows unauthenticated attackers to execute arbitrary commands by supplying a crafted objClass parameter containing shell metacharacters and output redir

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.