CVE-2021-47705

HIGH

COMMAX UMS Client ActiveX Control 1.7.0.2 - Buffer Overflow

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2021-47705. PoCs published by LiquidWorm.

AI-analyzed exploit summary This exploit demonstrates a heap-based buffer overflow in COMMAX UMS Client ActiveX Control (CNC_Ctrl.dll) by passing overly long strings to the 'rtsp_forceconnect_login' function, leading to arbitrary code execution. The PoC triggers an access violation and overwrites the exception handler, confirming the 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.

Exploits (1)

exploitdb WORKING POC
by LiquidWorm · textwebappshardware
https://www.exploit-db.com/exploits/50232

This exploit demonstrates a heap-based buffer overflow in COMMAX UMS Client ActiveX Control (CNC_Ctrl.dll) by passing overly long strings to the 'rtsp_forceconnect_login' function, leading to arbitrary code execution. The PoC triggers an access violation and overwrites the exception handler, confirming the vulnerability.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: COMMAX UMS Client ActiveX Control 1.7.0.2 (CNC_Ctrl.dll)
No auth needed
Prerequisites: Victim must open the malicious HTML file in Internet Explorer · COMMAX UMS Client ActiveX Control must be installed
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (4)

Core 4
Core References
Exploit, Third Party Advisory exploit
https://www.exploit-db.com/exploits/50232
Various Sources technical-description
https://www.commax.com
Third Party Advisory third-party-advisory
https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5664.php

Scores

CVSS v4 8.7
EPSS 0.0045
EPSS Percentile 35.4%
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-787
Status published
Products (1)
COMMAX Co., Ltd./COMMAX UMS Client ActiveX Control 1.7.0.2
Published Dec 09, 2025
Tracked Since Feb 18, 2026