Heap-based Buffer Overflow Vulnerability in COMMAX UMS Client ActiveX
CVE-2021-47705

8.7HIGH

Key Information:

Vendor

Commax Co., Ltd.

Status
Commax Ums Client Activex Control
Vendor
CVE Published:
9 December 2025

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2021-47705?

The COMMAX UMS Client ActiveX Control version 1.7.0.2 is susceptible to a heap-based buffer overflow vulnerability. This issue arises from improper boundary validation handled within the CNC_Ctrl.dll file, which allows attackers to manipulate string arrays by sending excessively long inputs through multiple functions. Exploiting this vulnerability can lead to heap corruption, potentially enabling attackers to execute arbitrary code and gain unauthorized system-level access, posing significant security risks.

Affected Version(s)

COMMAX UMS Client ActiveX Control 1.7.0.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2021-47705 - Proof of Concept

References

https://www.exploit-db.com/exploits/50232
exploit
https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-56...
third-party-advisory
https://www.commax.com
technical-description

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

LiquidWorm as Gjoko Krstic of Zero Science Lab
JSON
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CVE-2021-47705 : Heap-based Buffer Overflow Vulnerability in COMMAX UMS Client ActiveX