CVE-2026-129137 in PowerShell Universal
Summary
by MITRE • 11/14/2026
Incorrect default permissions in the agent configuration folder in Devolutions PowerShell Universal 2026.3.4 and earlier allows a local unprivileged user to execute arbitrary code as SYSTEM via a crafted agent configuration file that points the agent to an attacker-controlled server.
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Analysis
by VulDB Data Team • 11/14/2026
The vulnerability identified in Devolutions PowerShell Universal versions prior to 2026.3.4 stems from improper default permissions assigned to the agent configuration directory on Windows systems where the service is installed with elevated privileges, typically running as SYSTEM. This misconfiguration creates a path traversal and privilege escalation vector that allows local unprivileged users to manipulate critical system components without authentication or sufficient authorization checks. The core technical flaw lies in the fact that while the PowerShell Universal Agent service operates under high-privilege accounts such as Local System to execute administrative tasks, the configuration files governing its behavior are stored in directories where standard user accounts retain write access. This discrepancy between the execution context of the service and the file system permissions of its configuration data violates fundamental security principles regarding least privilege and secure default configurations.
An attacker with local unprivileged access can exploit this weakness by crafting a malicious agent configuration file that redirects the PowerShell Universal Agent to communicate with an external server controlled by the adversary. By modifying these configuration files, which are typically located in paths such as ProgramData or similar system directories depending on the installation method, the user effectively hijacks the trust relationship between the local service and its remote management endpoint. When the agent subsequently starts or reloads its configuration, it establishes a connection to the attacker-controlled server under the context of the SYSTEM account. This allows the adversary to inject arbitrary PowerShell commands that are then executed with full administrative privileges on the host machine, bypassing standard user-level restrictions entirely.
The operational impact of this vulnerability is severe, as it results in complete compromise of the affected system through remote code execution at the highest privilege level available within the Windows operating environment. Once an attacker achieves SYSTEM-level access via this mechanism, they can install rootkits, create persistent backdoors, dump credential hashes from memory using tools like Mimikatz, or pivot to other systems on the network with elevated trust relationships. This effectively neutralizes many perimeter defenses since the threat actor already possesses deep internal access that is difficult for endpoint detection solutions to distinguish from legitimate administrative activity unless specific behavioral analytics are in place. The ability to execute arbitrary code as SYSTEM also facilitates lateral movement and data exfiltration, significantly expanding the blast radius of an initial low-privilege foothold.
From a classification perspective, this issue aligns with CWE-250, which describes execution with unnecessary privileges, indicating that the software performs actions requiring higher-level permissions than necessary for its intended function due to poor configuration defaults. It also relates closely to CWE-732, concerning incorrect permission assignment for critical resources, as the root cause is the overly permissive access control list on the configuration directory rather than a logic error in code execution itself. In terms of adversary tactics and techniques, this vulnerability supports ATT&CK technique T1059 Command and Scripting Interpreter, specifically PowerShell abuse, allowing attackers to leverage native system tools for malicious purposes after gaining initial foothold through privilege escalation methods akin to T1068 Exploitation for Privilege Escalation.
Mitigation strategies must focus on correcting the file system permissions immediately upon deployment or upgrading of the software. Administrators should audit the configuration directories associated with PowerShell Universal Agents and ensure that only authorized service accounts, such as SYSTEM or specific administrative users, have write access to these folders. Standard user groups like Users or Guests should be explicitly denied write permissions while retaining read-only access if necessary for monitoring purposes but not modification. Additionally, implementing strict network segmentation can limit the impact by preventing agents from connecting to unauthorized external servers through firewall rules that restrict outbound traffic to known and trusted management endpoints only. Regular auditing of configuration files using integrity checking mechanisms such as Windows File Integrity Monitoring or third-party endpoint detection tools can also help detect unauthorized modifications before they are acted upon by the service, providing an additional layer of defense against this type of privilege escalation attack vector.