Remote Code Execution in Alexantr Filemanager

Executive Summary

CVE-2026-37637 is a Remote Code Execution (RCE) vulnerability in Alexantr filemanager version 1.0. It exists in the filemanager.php component due to insufficient validation of uploaded files.

This flaw allows a remote attacker to upload malicious PHP files into a web-accessible directory and execute arbitrary commands on the server by accessing the uploaded file through a browser.

The vulnerability arises because the application does not properly validate file extensions, MIME types, or file content, enabling attackers to upload files containing malicious code such as `<?php system($_GET['cmd']); ?>`.

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Compliance Impact

The vulnerability in Alexantr filemanager v1.0 allows remote attackers to execute arbitrary code on the server by uploading malicious PHP files. This can lead to unauthorized access, modification, or deletion of sensitive data stored on the server.

Such unauthorized access and potential data breaches can result in non-compliance with common standards and regulations like GDPR and HIPAA, which require protection of personal and sensitive information against unauthorized access and disclosure.

Therefore, exploitation of this vulnerability could compromise the confidentiality and integrity of sensitive data, leading to regulatory violations and possible legal and financial consequences.

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Impact Analysis

Successful exploitation of this vulnerability can allow attackers to execute arbitrary system commands on the server.

• Read sensitive files on the server.
• Modify or delete application files.
• Upload additional malware.
• Pivot further into the hosting environment, potentially leading to full server compromise.

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Detection Guidance

This vulnerability can be detected by monitoring for suspicious PHP files in web-accessible directories and looking for unusual request patterns that include command execution parameters.

• Check for unexpected PHP files in upload directories, especially those that may have been uploaded recently.
• Monitor web server logs for requests containing parameters like cmd=, exec=, or shell= which may indicate attempts to execute commands.
• Example command to find suspicious PHP files: `find /var/www/html/uploads -name '*.php'`
• Example command to search web server logs for command execution attempts: `grep -E 'cmd=|exec=|shell=' /var/log/apache2/access.log`

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Mitigation Strategies

Immediate mitigation steps include restricting and validating file uploads to prevent malicious files from being uploaded and executed.

• Block dangerous file extensions such as .php from being uploaded.
• Use allowlists to permit only safe file types.
• Validate MIME types and file content on the server side.
• Store uploaded files outside the web root to prevent direct access.
• Disable PHP execution in upload directories.
• Rename uploaded files to remove user-controlled extensions.
• Restrict upload functionality to trusted users only.

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