Path Traversal in OpenBMB ChatDev

Executive Summary

CVE-2026-58166 is a path traversal vulnerability in OpenBMB ChatDev versions up to 2.2.0. It occurs in the file upload handler where the application fails to properly sanitize filenames supplied in multipart upload requests.

Attackers can supply malicious filenames containing path traversal sequences (like ../../../) or absolute paths to the upload endpoint. Because the server constructs the destination file path without validation, this allows attackers to write or delete arbitrary files anywhere on the server filesystem.

The vulnerable endpoint is the POST /api/uploads/{session_id}, which requires only a session ID that can be obtained without authentication. This means unauthenticated remote attackers can exploit this flaw.

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Detection Guidance

This vulnerability can be detected by monitoring for suspicious POST requests to the upload endpoint that contain filenames with path traversal sequences or absolute paths.

Specifically, look for POST requests to the /api/uploads/{session_id} endpoint where the multipart filename includes patterns like ../../../ or absolute paths that attempt to escape the intended upload directory.

Since the session ID can be obtained without authentication, any unusual or unexpected upload activity to this endpoint should be investigated.

Commands to detect such activity might include using network monitoring tools or web server logs to filter for suspicious upload requests. For example:

• Using grep on web server logs to find suspicious filenames: grep -E 'POST /api/uploads/.*' access.log | grep -E '(\.\.\/|\/)'
• Using a network packet capture tool like tcpdump or Wireshark to filter HTTP POST requests to the upload endpoint and inspect multipart filenames for traversal sequences.
• Checking server filesystem for unexpected file creations or deletions outside the normal upload directory, especially files with names matching suspicious patterns.

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Impact Analysis

This vulnerability allows attackers to write or delete arbitrary files on the server hosting OpenBMB ChatDev. This can lead to serious impacts including:

• Overwriting critical system files such as shell configuration files or cron jobs, potentially enabling remote code execution.
• Deleting important files on the host system, which can disrupt service or cause data loss.
• Compromising the integrity and availability of the server by manipulating files outside the intended upload directory.

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Compliance Impact

The vulnerability allows unauthenticated remote attackers to write or delete arbitrary files on the server filesystem by exploiting a path traversal flaw in the file upload endpoint. This can lead to unauthorized modification or destruction of critical system files, potentially resulting in data integrity and availability issues.

Such unauthorized file manipulation can impact compliance with standards and regulations like GDPR and HIPAA, which require protection of data integrity, confidentiality, and availability. Specifically, the ability to overwrite or delete files could lead to loss or tampering of sensitive personal or health data, violating these regulations' mandates for secure data handling and breach prevention.

Therefore, organizations using affected versions of OpenBMB ChatDev may face increased risk of non-compliance due to this vulnerability if exploited, emphasizing the importance of applying the provided patch to mitigate these risks.

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Mitigation Strategies

The immediate mitigation step is to update OpenBMB ChatDev to a version that includes the fix from commit 4fd4da6, which sanitizes uploaded filenames to prevent path traversal.

If updating immediately is not possible, restrict access to the upload endpoint (/api/uploads/{session_id}) to trusted users or networks to prevent unauthenticated attackers from exploiting the vulnerability.

Additionally, monitor and audit file system changes to detect any unauthorized file writes or deletions caused by exploitation attempts.

Implement network-level protections such as web application firewalls (WAFs) to block requests containing path traversal sequences in filenames.

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