Executive Summary

This vulnerability exists in Flare, a Next.js-based file sharing platform. Before version 1.7.3, an authenticated path traversal flaw in the /api/avatars/[filename] endpoint allows any logged-in user to read arbitrary files within the application container.

The issue arises because the filename parameter is passed to path.join() without sanitization, and getFileStream() does not validate the path. This allows attackers to use encoded sequences like %2F to traverse directories (../) and access files outside the intended uploads/avatars/ directory.

Although authentication is required, instances with open registration (the default setting) allow any attacker to self-register and exploit this vulnerability immediately.

This vulnerability was fixed in version 1.7.3 of Flare.

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Impact Analysis

This vulnerability can allow an attacker who is able to log in (or self-register if open registration is enabled) to read arbitrary files within the application container.

Such unauthorized file access could lead to exposure of sensitive information stored on the server, including configuration files, user data, or other confidential files accessible to the Next.js process.

This could result in data breaches, loss of confidentiality, and potentially further exploitation depending on the contents of the accessed files.

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Compliance Impact

I don't know

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Detection Guidance

I don't know

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Mitigation Strategies

To mitigate this vulnerability, upgrade Flare to version 1.7.3 or later, where the path traversal issue in /api/avatars/[filename] is fixed.

If upgrading immediately is not possible, consider disabling open registration to prevent attackers from self-registering and exploiting the vulnerability.

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