CVE-2025-14265: ConnectWise ScreenConnect RCE Vulnerability

CVE-2025-14265 Overview

CVE-2025-14265 is a critical vulnerability in ConnectWise ScreenConnect that affects the server-side extension subsystem in versions prior to 25.8. The vulnerability stems from insufficient server-side validation and integrity checks, allowing authorized or administrative users to install and execute untrusted or arbitrary extensions. Successful exploitation could result in custom code execution on the server or unauthorized access to application configuration data.

Critical Impact

Administrative users can abuse weak extension validation to execute arbitrary code on ScreenConnect servers, potentially leading to complete server compromise and unauthorized access to sensitive configuration data.

Affected Products

• ConnectWise ScreenConnect versions prior to 25.8
• ScreenConnect server component (host and guest clients are not impacted)

Discovery Timeline

• 2025-12-11 - CVE-2025-14265 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2025-14265

Vulnerability Analysis

This vulnerability is classified under CWE-494 (Download of Code Without Integrity Check). The ScreenConnect server's extension subsystem fails to properly validate the integrity and trustworthiness of extensions before installation. When an authorized or administrative user attempts to install an extension, the server does not adequately verify that the extension originates from a trusted source or has not been tampered with.

The scope of this vulnerability extends beyond the vulnerable component itself, meaning that a compromised ScreenConnect server could potentially impact connected systems and expose sensitive application configuration data. The vulnerability requires high privileges to exploit, but once exploited, an attacker gains significant control over the server environment.

Root Cause

The root cause of CVE-2025-14265 lies in the absence of robust server-side integrity checks within the extension installation workflow. Prior to version 25.8, the ScreenConnect server did not enforce sufficient validation mechanisms to ensure that only trusted, verified extensions could be installed. This design flaw allowed administrative users to bypass intended security controls and install arbitrary extension packages.

Attack Vector

The attack leverages network access to the ScreenConnect administrative interface. An attacker with valid administrative credentials can craft or obtain a malicious extension package and upload it through the extension management functionality. Due to the missing integrity verification, the server accepts and executes the untrusted extension, allowing the attacker to:

1. Execute custom code within the server context
2. Access and potentially exfiltrate application configuration data
3. Establish persistence on the compromised server
4. Potentially pivot to connected systems

The exploitation scenario requires the attacker to possess administrative access to the ScreenConnect server, which could be obtained through credential theft, phishing, or other initial access techniques.

Detection Methods for CVE-2025-14265

Indicators of Compromise

• Unexpected or unauthorized extensions appearing in the ScreenConnect extension directory
• Unusual server processes spawned by the ScreenConnect service
• Modifications to application configuration files outside of normal administrative activity
• Anomalous network connections originating from the ScreenConnect server

Detection Strategies

• Monitor extension installation logs for unauthorized or unexpected extension deployments
• Implement file integrity monitoring on the ScreenConnect extension directory and configuration files
• Review administrative user activity logs for unusual extension management operations
• Deploy endpoint detection and response (EDR) solutions to identify malicious code execution patterns

Monitoring Recommendations

• Enable verbose logging for ScreenConnect administrative actions and extension management
• Configure alerts for any extension installation events, especially outside of maintenance windows
• Establish baseline behavior for the ScreenConnect server process and alert on deviations
• Monitor outbound network connections from the ScreenConnect server for suspicious destinations

How to Mitigate CVE-2025-14265

Immediate Actions Required

• Upgrade to ScreenConnect version 25.8 or later immediately
• Audit all currently installed extensions and remove any untrusted or unrecognized packages
• Review administrative user accounts and remove unnecessary privileges
• Implement multi-factor authentication for all administrative access to ScreenConnect

Patch Information

ConnectWise has released ScreenConnect version 25.8 which introduces enhanced server-side configuration handling and integrity checks to ensure only trusted extensions can be installed. Organizations should upgrade to this version as soon as possible. For detailed patch information, refer to the ConnectWise Security Patch Bulletin.

Workarounds

• Restrict administrative access to ScreenConnect to a minimal set of trusted users
• Implement network segmentation to limit access to the ScreenConnect administrative interface
• Deploy application whitelisting on the ScreenConnect server to prevent unauthorized code execution
• Consider disabling extension installation capabilities until the patch can be applied

# Verify ScreenConnect version and check for updates
# Navigate to ScreenConnect administration panel
# Administration > General > About
# Ensure version displays 25.8 or later
# If using on-premises deployment, download latest installer from ConnectWise