Path Traversal in mail-mcp-bridge

Executive Summary

This vulnerability is a flaw in the fatbobman mail-mcp-bridge software up to version 1.3.3, specifically in an unknown function within the file src/mail_mcp_server.py. It involves manipulation of the argument message_ids, which can lead to a path traversal attack. This means an attacker can remotely exploit this flaw to access files or directories outside the intended scope.

The vulnerability can be exploited remotely without any authentication, and an exploit has already been published. Upgrading to version 1.3.4, which includes a patch, resolves this issue.

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Detection Guidance

This vulnerability involves path traversal via manipulation of message_ids leading to unauthorized directory access and deletion. Detection involves monitoring for suspicious message_id inputs containing path traversal sequences such as "../" or other directory escape tokens.

You can check logs or inputs to the mail-mcp-bridge cleanup tool or attachment extraction processes for message IDs containing path traversal patterns.

Suggested commands to detect potential exploitation attempts include searching for suspicious message IDs in logs or runtime inputs, for example:

• grep -r '\.\./' /path/to/mail-mcp-bridge/logs
• grep -r 'message_id=.*\.\./' /var/log/syslog
• Monitor filesystem changes or deletions in directories adjacent to the mail-mcp-bridge attachment directories using tools like inotifywait or auditd.

Additionally, reviewing the source or running tests similar to those in the test_attachment_path_safety.py can help verify if the system is vulnerable.

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Impact Analysis

This vulnerability can allow an attacker to perform a path traversal attack remotely, potentially accessing sensitive files or directories on the affected system that should not be accessible. This can lead to unauthorized disclosure of information, modification, or deletion of files, which may compromise the integrity and confidentiality of the system.

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Compliance Impact

The vulnerability CVE-2026-7386 involves a path traversal flaw that allows remote attackers to manipulate message IDs to perform unauthorized directory deletions and access. This can lead to integrity and availability issues by deleting critical directories or files.

While the provided context and resources do not explicitly mention compliance with standards such as GDPR or HIPAA, the integrity and availability impacts caused by this vulnerability could potentially affect compliance. For example, unauthorized deletion or manipulation of email data could violate data protection and security requirements mandated by these regulations.

Mitigations such as upgrading to version 1.3.4, which includes secure handling of attachment paths and input validation, help reduce the risk of data loss or unauthorized access, thereby supporting compliance efforts.

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Mitigation Strategies

The recommended immediate step to mitigate this vulnerability is to upgrade the affected component, fatbobman mail-mcp-bridge, to version 1.3.4 or later.

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