CVE-2021-47705 - CVE House

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Status published High CVE-2021-47705

CNC_Ctrl DllUnregisterServer Access Violation

8.7 CVSS

Vulnerability Description

COMMAX UMS Client ActiveX Control 1.7.0.2 contains a heap-based buffer overflow vulnerability that allows attackers to execute arbitrary code by providing excessively long string arrays through multiple functions. Attackers can exploit improper boundary validation in CNC_Ctrl.dll to cause heap corruption and potentially gain system-level access.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

LiquidWorm as Gjoko Krstic of Zero Science Lab

References

More from COMMAX Co., Ltd.

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COMMAX Smart Home Ruvie CCTV Bridge DVR Service RTSP Credentials Disclosure

COMMAX Smart Home Ruvie CCTV Bridge DVR Service Config Write / DoS

COMMAX Smart Home IoT Control System SQL Injection Authentication Bypass

Affected Vendor

COMMAX Co., Ltd.

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Affected Software

COMMAX UMS Client ActiveX Control

Vulnerable Versions:

1.7.0.2

Timeline

Official Publish: December 9th, 2025

Last Modified: April 7th, 2026

Added to House: July 21st, 2026

CVSS Vectors

Weaknesses (CWE)

MITRE ATT&CK TTPs

T1190 Exploit Public-Facing Application

T1068 Exploitation for Privilege Escalation

Privilege Escalation

T1055 Process Injection

Defense Evasion

T1105 Ingress Tool Transfer

Command and Control

T1485 Data Destruction