CVE-2021-47705 CNC_Ctrl DllUnregisterServer Access Violation
Heap-based buffer overflow in COMMAX UMS Client ActiveX Control allows attackers to execute arbitrary code via long string arrays.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2021-47705?
CVE-2021-47705 is a high-severity memory corruption vulnerability in COMMAX UMS Client ActiveX Control, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-787
Which versions are affected by CVE-2021-47705?
How do I fix CVE-2021-47705?
No fix has been published for CVE-2021-47705 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2021-47705 being exploited?
There is no known exploitation of CVE-2021-47705 in the wild and no public exploit code.
Sources
Also known as GHSA-hx89-cwv8-4xch.