CNC_Ctrl DllUnregisterServer f5501 Access Violation

published 2025-12-09 10 mo ago modified 2026-06-17 4 mo ago also EUVD-2021-34726

cvss: 8.7; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits: 0; none known

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.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 10 mo ago (2025-12-12)

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

exploit-db.com https://www.exploit-db.com/exploits/50231 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.7	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
CNA	4.0	8.7	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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

COMMAX Co., Ltd. COMMAX WebViewer ActiveX Control

Classification

Weakness

CWE-787 Out-of-bounds Write

References

exploit-db.com /exploits/50231
exploit
zeroscience.mk /en/vulnerabilities/ZSL-2021-5663.php
third-party-advisory
commax.com
product
vulncheck.com /advisories/commax-webviewer-activex-control-commax-webviewer-ocx-buffer-overflow
third-party-advisory

Sources

CVE List CVE-2021-47719
NVD CVE-2021-47719

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary