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

> Unauthenticated attackers can execute arbitrary commands via the Reporter component to achieve remote code execution on Tianxin Internet Behavior Management Systems.

- **Severity:** Critical 9.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Apr 2026
- **Updated:** 14 May 2026
- **Also known as:** GHSA-qr68-g3cq-vhr2

## What is CVE-2021-4473?

CVE-2021-4473 is a critical command injection vulnerability in Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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).

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2021-4473?

It affects 1 product.


Products: Topsecgroup Tianxin Internet Behavior Management System.

## How do I fix CVE-2021-4473?

No fix has been published for CVE-2021-4473 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-4473 being exploited?

There is no known exploitation of CVE-2021-4473 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4473 and fix it if it is affected.

What it is: CVE-2021-4473 is a critical command injection vulnerability in Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-4473 in the wild and no public exploit code.

Affected product: Beijing Topsec Network Security Technology Co., Ltd. Tianxin Internet Behavior Management System. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-4473/ (Markdown: https://insights.sbomify.com/CVE-2021-4473/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4473
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4473
- OSV: https://osv.dev/vulnerability/CVE-2021-4473

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4473/
Summaries are generated and may contain mistakes; the official description above is the record.