ConnectWise ScreenConnect contains an improper authentication vulnerability. This vulnerability could allow a ViewState code injection attack, which could allow remote code execution if machine keys are compromised.

In versions of ScreenConnect™ prior to 25.8, server-side validation and integrity checks within the extension subsystem could allow the installation and execution of untrusted or arbitrary extensions by authorized or administrative users. Abuse of this behavior could result in the execution of custom code on the server or unauthorized access to application configuration data. This issue affects only the ScreenConnect server component; host and guest clients are not impacted. ScreenConnect 25.8 introduces enhanced server-side configuration handling and integrity checks to ensure only trusted extensions can be installed.

In deployments using the ScreenConnect™ Certificate Signing Extension, encrypted configuration values including an Azure Key Vault-related key, could be returned to unauthenticated users through a client-facing endpoint under certain conditions. The values remained encrypted and securely stored at rest; however, an encrypted representation could be exposed in client responses. Updating the Certificate Signing Extension to version 1.0.12 or higher ensures configuration handling occurs exclusively on the server side, preventing encrypted values from being transmitted to or rendered by client-side components.