Cloudreve Remote Downloader Path Traversal Vulnerability

Executive Summary

Cloudreve before version 4.16.1 has a path traversal vulnerability where it fails to sanitize file paths from remote downloaders. Authenticated users can exploit this by including sequences like '../' in downloader metadata to write files outside the intended destination directory within accessible namespaces.

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Detection Guidance

To detect this vulnerability, monitor Cloudreve logs for unusual file paths containing traversal sequences like '../' in remote downloader metadata. Check for files created outside intended directories by comparing actual file locations with expected paths. Review system logs for unauthorized file writes in sensitive directories.

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Impact Analysis

This vulnerability allows attackers with remote-download permissions to place files in unintended locations within accessible directories. While files remain subject to Cloudreve's permission checks, it could lead to unauthorized file creation or overwriting in restricted areas.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by allowing unauthorized file creation outside designated directories. For GDPR, improper file handling may risk unauthorized data access or storage in unintended locations, violating data protection principles. For HIPAA, if sensitive health data is involved, this flaw could lead to unauthorized storage or exposure of protected health information outside controlled directories.

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Mitigation Strategies

Immediately upgrade Cloudreve to version 4.16.1 or later to patch the vulnerability. Disable remote download functionality if not required. Implement strict input validation for file paths in downloaders. Restrict write permissions to prevent unauthorized file creation outside intended directories.

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