Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-25866 is a vulnerability in MobaXterm versions prior to 26.1 where the application calls the Windows API function WinExec to launch Notepad++ without specifying a fully qualified executable path when opening remote files.'}, {'type': 'paragraph', 'content': "This improper handling of the executable path allows an attacker to exploit the search path behavior by placing a malicious executable earlier in the system's search order."}, {'type': 'paragraph', 'content': 'As a result, the attacker can execute arbitrary code with the privileges of the affected user.'}] [1]

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Impact Analysis

This vulnerability can lead to arbitrary code execution in the context of the affected user, meaning an attacker with local access and the required privileges can run malicious code on your system.

The impact includes high severity risks to confidentiality, integrity, and availability of your system and data.

• Confidentiality: An attacker could access sensitive information.
• Integrity: An attacker could modify or corrupt data.
• Availability: An attacker could disrupt system operations.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'The vulnerability involves MobaXterm calling WinExec to execute Notepad++ without a fully qualified path, which can be exploited by placing a malicious executable earlier in the search path. Detection would involve checking the version of MobaXterm installed and verifying if it is prior to version 26.1.'}, {'type': 'paragraph', 'content': 'To detect this vulnerability on your system, you can check the installed MobaXterm version by running the application and viewing its About section or by checking the executable properties.'}, {'type': 'paragraph', 'content': 'Additionally, you can search your system for unquoted service paths or executable calls related to Notepad++ that do not use fully qualified paths.'}, {'type': 'paragraph', 'content': 'Specific commands to help detect this issue might include:'}, {'type': 'list_item', 'content': 'Check MobaXterm version: Run MobaXterm and check the About dialog or use command line to check the version if supported.'}, {'type': 'list_item', 'content': "Search for unquoted paths in services: Use PowerShell command `Get-WmiObject win32_service | where {$_.PathName -like '*notepad++*'} | select Name, PathName` to find services calling Notepad++ without quotes."}, {'type': 'list_item', 'content': 'Check for suspicious executables in directories earlier in the PATH environment variable that could be executed instead of the legitimate Notepad++.'}] [1]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'The primary mitigation step is to update MobaXterm to version 26.1 or later, where the vulnerability has been fixed by using fully qualified executable paths.'}, {'type': 'paragraph', 'content': 'Until the update can be applied, restrict local user privileges to prevent placing malicious executables in directories earlier in the search path.'}, {'type': 'paragraph', 'content': "Additionally, review and harden the system's PATH environment variable to ensure no untrusted directories precede system directories."}, {'type': 'paragraph', 'content': 'Consider monitoring and restricting execution of unauthorized executables in directories that are part of the search path.'}] [1]

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