A critical path traversal vulnerability in mail-mcp-bridge permits unauthenticated attackers to perform unauthorized file system operations, including the deletion of arbitrary directories.

The application fails to properly sanitize the message_ids argument passed to the cleanup_attachments tool, allowing the use of path traversal sequences. An unauthenticated attacker can supply crafted input to escape the intended attachment cache directory and trigger a recursive deletion of arbitrary directories on the host.

Successful exploitation of this vulnerability poses a severe risk to data integrity and system availability. By leveraging the application's own file management functions, an attacker can delete critical application data, configuration files, or other sensitive directories residing on the host, potentially leading to service disruption or total system compromise. Given the CVSS score of 7.3 and the nature of the impact, this should be treated as a high-priority remediation task.

Immediate Action: Upgrade the mail-mcp-bridge component to version 1.3.4 or later immediately.

Proactive Monitoring: Review application logs for suspicious MCP tool calls containing path traversal characters like "../" within the message_ids parameter.

Compensating Controls: If an immediate update is not feasible, restrict network access to the MCP interface to trusted IP addresses only, or disable the cleanup_attachments tool functionality until the patch is applied.

Public Exploit Available: Yes, a proof-of-concept is documented in the researcher's GitHub issue report at https://github.com/fatbobman/mail-mcp-bridge/issues/2.

The presence of a public proof-of-concept combined with the ability for remote, unauthenticated attackers to delete arbitrary files makes this a significant security risk. Organizations running mail-mcp-bridge must prioritize updating to version 1.3.4 to eliminate the underlying path traversal flaw. Failure to patch may expose the host environment to destructive actions that could cripple business operations.