CVE-2021-4473

Name: CVE-2021-4473
Creator: NVD / NIST
Published: 2026-04-07T13:16:44.54+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.3/10EPSS 6.17%

Last modified Jun 17, 2026

CVE-2021-4473 is a critical-severity vulnerability rated 9.3/10 on the CVSS scale. 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. EPSS estimates a 6.17% chance of exploitation in the next 30 days.

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).

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS 4.0

9.3/10

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

6.17%

92.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-78

Affected Software

Vendor	Product	Versions
Topsecgroup	Tianxin Internet Behavior Management System	< 4.0.0.7_20210716.180815

References

https://avd.aliyun.com/detail?id=AVD-2021-890232Third Party Advisory
https://cn-sec.com/archives/4631959.htmlExploit, Third Party Advisory
https://www.cnvd.org.cn/flaw/show/CNVD-2021-41972Third Party Advisory
https://www.cnvd.org.cn/patchInfo/show/280166Patch
https://www.vulncheck.com/advisories/tianxin-internet-behavior-management-system-command-injection-via-toquery-phpThird Party Advisory, VDB Entry

Timeline

Published: Apr 7, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-4473?

How severe is CVE-2021-4473?

CVE-2021-4473 has a CVSS score of 9.3/10 (CRITICAL severity). The EPSS model estimates a 6.17% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4473?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-4473?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST