CVE-2021-47794

HighPublic PoCRCE

Published: 16 January 2026

Published

16 January 2026

Modified

21 January 2026

KEV Added

—

Patch

—

CVSS Score 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0019 40.1th percentile

Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-47794 is a high-severity OS Command Injection (CWE-78) vulnerability in Zesle Zeslecp. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 40.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 AC-6 (Least Privilege) and SI-10 (Information Input Validation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Directly mitigates OS command injection in the FTP account creation endpoint by requiring validation and sanitization of user inputs to prevent shell payload execution.

SI-2 Flaw Remediation good match

prevent

Requires timely identification, reporting, and correction of flaws like CVE-2021-47794 through patching and integration with configuration management.

AC-6 Least Privilege good match

prevent

Enforces least privilege to restrict low-privilege authenticated users from accessing the vulnerable FTP account creation endpoint, blocking exploitation.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1059.004 Unix Shell Execution

Adversaries may abuse Unix shell commands and scripts for execution.

attack.mitre.org →

Why these techniques?

CVE enables exploitation of a public-facing web application (T1190) via authenticated OS command injection in FTP account creation endpoint, facilitating Unix shell command execution (T1059.004) for RCE such as reverse shells.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

ZesleCP 3.1.9 contains an authenticated remote code execution vulnerability that allows attackers to create malicious FTP accounts with shell injection payloads. Attackers can exploit the FTP account creation endpoint by injecting a reverse shell command that establishes a network connection…

to a specified listening host.

Deeper analysisAI

CVE-2021-47794 is an authenticated remote code execution vulnerability in ZesleCP 3.1.9, published on 2026-01-16. The issue, tied to CWE-78 (OS Command Injection), has a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). It arises in the FTP account creation endpoint, where attackers can inject shell payloads into malicious FTP accounts.

Authenticated attackers with low privileges (PR:L) can exploit the vulnerability over the network with low complexity and no user interaction required. By submitting a reverse shell command via the FTP account creation endpoint, they establish a network connection to a listener host under their control, achieving full remote code execution with high impacts on confidentiality, integrity, and availability.

Advisories and proof-of-concept exploits are available, including at https://www.exploit-db.com/exploits/50233 and https://www.vulncheck.com/advisories/zeslecp-remote-code-execution-rce-authenticated. A demonstration video exists at https://www.youtube.com/watch?v=5lTDTEBVq-0, and the vendor site is https://zeslecp.com/.