CVE-2026-39454: SKYSEA Client View RCE Vulnerability

CVE-2026-39454 Overview

SKYSEA Client View and SKYMEC IT Manager, enterprise asset management solutions provided by Sky Co., LTD., contain an insecure permissions vulnerability (CWE-276) in their installation folder configuration. The products configure installation directories with improper file access permission settings, allowing non-administrative users to manipulate and place arbitrary files within the installation folder. This vulnerability enables local privilege escalation, resulting in arbitrary code execution with administrative privileges.

Critical Impact

Local attackers with low-level user access can escalate privileges to administrative level by exploiting weak file permissions in the installation directory, potentially leading to complete system compromise.

Affected Products

• SKYSEA Client View (versions prior to security update)
• SKYMEC IT Manager (versions prior to security update)
• Sky Co., LTD. enterprise management software installations with default configurations

Discovery Timeline

• 2026-04-20 - CVE-2026-39454 published to NVD
• 2026-04-20 - Last updated in NVD database

Technical Details for CVE-2026-39454

Vulnerability Analysis

This vulnerability stems from improper permission configuration during the installation process of SKYSEA Client View and SKYMEC IT Manager. When these enterprise asset management applications are installed, the installation folder is configured with overly permissive access controls that fail to restrict write access to non-administrative users.

The insecure permissions allow any authenticated local user to modify existing files or place new files within the installation directory. Since these applications run services or components with elevated privileges, an attacker can leverage this weakness to achieve code execution in the context of the SYSTEM account or administrative user.

Root Cause

The root cause is CWE-276: Incorrect Default Permissions. The installation routine for both SKYSEA Client View and SKYMEC IT Manager fails to properly configure Access Control Lists (ACLs) on the installation directory. Instead of restricting write permissions to administrators only, the installer grants excessive permissions that allow standard users to modify the application's files, libraries, or configuration.

This misconfiguration is particularly dangerous in enterprise environments where these tools are deployed across multiple endpoints, as it creates a consistent attack surface on every installation.

Attack Vector

The attack requires local access to an affected system with a low-privileged user account. An attacker can exploit this vulnerability through the following approach:

The attacker first identifies the installation directory of SKYSEA Client View or SKYMEC IT Manager on the target system. Due to the improper permissions, they can then either replace legitimate executable files or DLLs with malicious versions, or place a malicious DLL that will be loaded by the application through DLL search order hijacking. When the affected service restarts or the application executes, the malicious code runs with administrative privileges, completing the privilege escalation attack.

This attack does not require user interaction beyond the attacker having initial access to a user session on the vulnerable system. The exploitation is straightforward once the vulnerable installation is identified.

Detection Methods for CVE-2026-39454

Indicators of Compromise

• Unexpected file modifications within SKYSEA Client View or SKYMEC IT Manager installation directories
• New DLL or executable files appearing in the installation folder with recent timestamps
• Changes to legitimate application binaries indicated by hash mismatches
• Unusual process behavior from SKYSEA or SKYMEC services executing unexpected child processes

Detection Strategies

• Audit file permission changes on enterprise management software installation directories using Windows Security Event logs
• Monitor for file creation or modification events in protected application directories using endpoint detection tools
• Implement file integrity monitoring (FIM) on SKYSEA Client View and SKYMEC IT Manager installation folders
• Configure SentinelOne to detect suspicious DLL loads or binary modifications in monitored application paths

Monitoring Recommendations

• Enable verbose logging for file system access on application installation directories
• Configure alerts for privilege escalation patterns originating from SKYSEA or SKYMEC processes
• Regularly audit ACLs on installation directories to ensure proper permission configuration
• Monitor service restarts of affected applications that may indicate exploitation attempts

How to Mitigate CVE-2026-39454

Immediate Actions Required

• Apply the latest security update from Sky Co., LTD. as referenced in the SkySea Client View Update
• Review and correct file permissions on existing SKYSEA Client View and SKYMEC IT Manager installations
• Restrict installation directory permissions to administrators only pending vendor patch deployment
• Monitor affected systems for signs of exploitation using endpoint detection capabilities

Patch Information

Sky Co., LTD. has released a security update addressing this vulnerability. Organizations should apply the update immediately to all affected installations. For detailed patch information and download links, refer to the SkySea Client View Update and the JVN Security Advisory for comprehensive vulnerability details.

Workarounds

• Manually configure restrictive ACLs on the installation folder, removing write permissions for non-administrative users
• Implement application whitelisting to prevent unauthorized executables from running within the installation directory
• Deploy file integrity monitoring to detect unauthorized modifications to application files
• Consider running affected services with minimal required privileges while awaiting vendor patches

# Configuration example - Restrict permissions on Windows installation folder
# Run in elevated PowerShell to correct insecure permissions
$installPath = "C:\Program Files\SKYSEA Client View"
icacls $installPath /inheritance:r
icacls $installPath /grant:r "BUILTIN\Administrators:(OI)(CI)F"
icacls $installPath /grant:r "NT AUTHORITY\SYSTEM:(OI)(CI)F"
icacls $installPath /grant:r "BUILTIN\Users:(OI)(CI)RX"