Is CVE-2021-4473 in the CISA KEV catalog?

No. CVE-2021-4473 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-4473?

CVE-2021-4473 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2021-4473?

CVE-2021-4473 has an EPSS score of 6.17% (93th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-4473

CRITICALEPSS 93th pctl

9.8

CVSS v3

NVD

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).

CWE-78OS Command Injection

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

6.17%probability of exploitation in 30 days

93rdpercentile

High risk: more likely to be exploited than 93% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-24.