How severe is CVE-2021-4473?

CVE-2021-4473 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-4473 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4473?

CVE-2021-4473 affects Topsecgroup Tianxin Internet Behavior Management System. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-4473?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2021-4473 have an EU (EUVD) identifier?

Yes. CVE-2021-4473 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34776.

When was CVE-2021-4473 published?

CVE-2021-4473 was published on 2026-04-07 and last updated on 2026-06-17.

CVE-2021-4473

CVE-2021-4473 is a critical-severity vulnerability in Topsecgroup Tianxin Internet Behavior Management System with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 9.3
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-34776
Weakness: CWE-78
Affected product: Topsecgroup Tianxin Internet Behavior Management System
Published: 2026-04-07
Last modified: 2026-06-17

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).

Frequently asked questions

What is CVE-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 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).
How severe is CVE-2021-4473?: CVE-2021-4473 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-4473 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4473?: CVE-2021-4473 affects Topsecgroup Tianxin Internet Behavior Management System. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-4473?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2021-4473 have an EU (EUVD) identifier?: Yes. CVE-2021-4473 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34776.
When was CVE-2021-4473 published?: CVE-2021-4473 was published on 2026-04-07 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:topsecgroup:tianxin_internet_behavior_management_system:*:*:*:*:*:*:*:*

Other CWE-78 (OS Command Injection) vulnerabilities

CVE-2026-56004 — Critical (CVSS 10.0): A shellcode injection in the mercurial handler of the obs tar_scm source service before version 0.12.4 could be used by…
CVE-2026-56415 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability within the debug.pl script that is…
CVE-2026-56413 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability in the ms_service.pl service, which listens…
CVE-2026-49869 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, AuthenticationFilter in…
CVE-2026-49261 — Critical (CVSS 10.0): MariaDB server is a community developed fork of MySQL server. Versions 10.6.1 through 10.6.26, 10.11.1 through…
CVE-2026-10520 — Critical (CVSS 10.0): An OS Command Injection vulnerability in Ivanti Sentry before the R10.5.2, R10.6.2 and R10.7.1 versions allows a…

Browse all CWE-78 (OS Command Injection) vulnerabilities →