Arbitrary code execution via unchecked RTSP login strings
Published Dec 9, 2025 · Updated Apr 7, 2026
Heap-based buffer overflow in CNC_Ctrl.dll in COMMAX UMS Client ActiveX Control 1.7.0.2 allows remote attackers to execute arbitrary code. The rtsp_forceconnect_login and rtsp_connect_login methods process oversized user_id, user_pwd, and rtsp_addr strings without validating their lengths, corrupting heap memory. A crafted web page must instantiate the 32-bit ActiveX control in Internet Explorer; successful exploitation runs code in the browser host's security context.
Summary
What happened
Heap-based buffer overflow in CNC_Ctrl.dll in COMMAX UMS Client ActiveX Control 1.7.0.2 allows remote attackers to execute arbitrary code. The rtsp_forceconnect_login and rtsp_connect_login methods process oversized user_id, user_pwd, and rtsp_addr strings without validating their lengths, corrupting heap memory. A crafted web page must instantiate the 32-bit ActiveX control in Internet Explorer; successful exploitation runs code in the browser host's security context.
The record
- CVE
- CVE-2021-47705
- Published
- Dec 9, 2025
- Updated
- Apr 7, 2026
- Vendor
- COMMAX
- Product
- COMMAX UMS Client ActiveX Control
- Classifications
- CWE-787, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 9, 2025CVE publishedPublication date reported by the CVE source.
- Apr 7, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.7.0.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- COMMAX UMS Client ActiveX Control CNC_Ctrl.dll heap overflow proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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