CVE-2021-47719 CNC_Ctrl DllUnregisterServer f5501 Access Violation
Attackers can execute arbitrary code via buffer overflow in COMMAX WebViewer ActiveX Control by providing excessively 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-2021-47719?
CVE-2021-47719 is a high-severity memory corruption vulnerability in COMMAX WebViewer 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 WebViewer ActiveX Control 2.1.4.5 contains a buffer overflow vulnerability that allows attackers to execute arbitrary code by providing excessively long string arrays through multiple functions. Attackers can exploit boundary errors in Commax_WebViewer.ocx to cause buffer overflow conditions and potentially gain code execution.
Weakness: CWE-787
Which versions are affected by CVE-2021-47719?
How do I fix CVE-2021-47719?
No fix has been published for CVE-2021-47719 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-2021-47719 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47719 exists.
Sources
Also known as GHSA-frh6-7cwp-hqh4.