Mitigation Strategies

The primary mitigation step is to update Cerberus FTP Server to version 2026.1 or later, where this vulnerability has been resolved.

Until the update can be applied, you should restrict write permissions on the installers directory (C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers) to prevent low-privileged users from creating or modifying files there.

Additionally, avoid running the update process from low-privileged user accounts to reduce the risk of exploitation.

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Executive Summary

CVE-2026-6265 is a local privilege escalation vulnerability in Cerberus FTP Server on Windows. It occurs because the software update process downloads update files into a directory that inherits writable permissions from a higher-level folder, allowing low-privileged users to create and control files there.

Specifically, the update installer is saved in the folder C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers, which inherits permissions from C:\ProgramData\ that allow standard users to create and write files. A low-privileged user can pre-create a malicious executable with the same predictable filename as the update installer.

When the update process runs with local administrator privileges, it overwrites the malicious file but the original user retains ownership and permissions, enabling them to swap the legitimate executable with their malicious one. This race condition allows the malicious executable to be executed with elevated privileges, resulting in local administrator privilege escalation.

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Impact Analysis

This vulnerability allows a low-privileged user on a system running Cerberus FTP Server to escalate their privileges to local administrator level. This means an attacker with limited access could execute malicious code with administrative rights.

With elevated privileges, the attacker could potentially take full control of the affected system, install malware, access sensitive data, modify system configurations, or disrupt services.

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Detection Guidance

This vulnerability involves insecure permissions on the update installers directory used by Cerberus FTP Server on Windows. Detection involves checking the permissions of the folder where update executables are downloaded.

Specifically, you should inspect the permissions of the directory: C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers to see if standard users (BUILTIN\Users) have write or create permissions.

On a Windows system, you can use the following commands to check permissions:

• icacls "C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers"
• PowerShell command to check ACLs: Get-Acl -Path "C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers" | Format-List

If the output shows that standard users have write or modify permissions on this directory, the system is vulnerable to this privilege escalation issue.

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Compliance Impact

The vulnerability allows local privilege escalation by enabling a low-privileged user to execute malicious code with administrative rights on the affected Cerberus FTP Server. This could lead to unauthorized access or modification of sensitive data managed by the server.

Such unauthorized privilege escalation and potential data compromise can negatively impact compliance with common standards and regulations like GDPR and HIPAA, which require strict access controls and protection of sensitive information.

Remediation by updating to the patched version is necessary to mitigate these risks and maintain compliance.

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