CVE-2025-66266 Insecure SYSTEM Service Permissions in UPSilon2000V6.0 (RupsMon.exe) leading to trivial Local Privilege Escalation
Local attackers can escalate privileges to SYSTEM by replacing the RupsMon.exe service executable due to insecure file permissions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-66266?
CVE-2025-66266 is a critical vulnerability in MegaTec Taiwan UPSilon2000V6.0, published on 26 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
The RupsMon.exe service executable in UPSilon 2000 has insecure permissions, allowing the 'Everyone' group Full Control. A local attacker can replace the executable with a malicious binary to execute code with SYSTEM privileges or simply change the config path of the service to a command; starting and stopping the service to immediately achieve code execution and privilege escalation
Weakness: CWE-269
Which versions are affected by CVE-2025-66266?
How do I fix CVE-2025-66266?
No fix has been published for CVE-2025-66266 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-66266 being exploited?
There is no known exploitation of CVE-2025-66266 in the wild and no public exploit code.
Sources
Also known as GHSA-9553-998g-436x.