How severe is CVE-2025-66266?

CVE-2025-66266 has a CVSS 4.0 base score of 9.3, rated critical severity.

Is CVE-2025-66266 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-66266?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2025-66266 have an EU (EUVD) identifier?

Yes. CVE-2025-66266 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-199688.

When was CVE-2025-66266 published?

CVE-2025-66266 was published on 2025-11-26 and last updated on 2026-06-17.

CVE-2025-66266

CVE-2025-66266 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-269.

Key facts

Severity: Critical (CVSS 4.0 base score 9.3)
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-199688
Weakness: CWE-269
Published: 2025-11-26
Last modified: 2026-06-17

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

Frequently asked questions

What is CVE-2025-66266?: 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
How severe is CVE-2025-66266?: CVE-2025-66266 has a CVSS 4.0 base score of 9.3, rated critical severity.
Is CVE-2025-66266 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-66266?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-66266 have an EU (EUVD) identifier?: Yes. CVE-2025-66266 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-199688.
When was CVE-2025-66266 published?: CVE-2025-66266 was published on 2025-11-26 and last updated on 2026-06-17.

References

https://www.megatec.com.tw/software-download/

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