CVE-2025-66266

SYSTEM privilege escalation via writable service executable

Published Nov 26, 2025 · Updated Nov 26, 2025

Improper privilege management in MegaTec UPSilon2000 6.0.5 allows local users to execute code with SYSTEM privileges through its service. The RupsMon.exe service grants Everyone Full Control, permitting its binary to be replaced or its executable path to be changed to a command. Local access is required; restarting the service runs attacker-controlled code as SYSTEM and can compromise the host.

CVSS severity9.3
Critical
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper privilege management in MegaTec UPSilon2000 6.0.5 allows local users to execute code with SYSTEM privileges through its service. The RupsMon.exe service grants Everyone Full Control, permitting its binary to be replaced or its executable path to be changed to a command. Local access is required; restarting the service runs attacker-controlled code as SYSTEM and can compromise the host.

The record

CVE
CVE-2025-66266
Published
Nov 26, 2025
Updated
Nov 26, 2025
Vendor
Mega System Technologies Inc.
Product
UPSilon2000
Classifications
CWE-269, T1574.010
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 26, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 26, 2025Record 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.

  1. Affected versionversion=6.0.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Mega System Technologies Inc. · UPSilon2000version=6.0.5

Published CVSS scores

9.3GridwareCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-269Improper Privilege Management
T1574.010Hijack Execution Flow: Services File Permissions Weakness

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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