Executive Summary

This vulnerability in Traefik affects versions prior to 2.11.32 and 2.11.31 through 3.6.2, where requests using PathPrefix, Path, or PathRegex matchers can bypass path normalization. Specifically, when Traefik uses path-based routing, requests containing URL-encoded restricted characters such as /, \, Null, ;, ?, and # can bypass the middleware chain and reach unintended backend services. For example, a request to a URL like http://mydomain.example.com/admin%2F could reach a backend service without triggering the intended security middleware for the /admin/ path, effectively bypassing security controls. This issue is fixed in versions 2.11.32 and 3.6.3.

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Impact Analysis

This vulnerability can allow attackers to bypass security middleware and access backend services that should be protected. By exploiting the path normalization bypass, unauthorized requests can reach unintended backends, potentially exposing sensitive data or functionality that should be restricted. This can lead to unauthorized access, data leakage, or other security breaches depending on the backend services involved.

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Mitigation Strategies

Upgrade Traefik to version 2.11.32 or later, or 3.6.3 or later, as these versions contain the fix for the path normalization bypass vulnerability.

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Detection Guidance

This vulnerability can be detected by monitoring for HTTP requests that contain URL-encoded restricted characters such as %2F (encoded slash), %00 (null byte), %3B (semicolon), %3F (question mark), or %23 (hash) in the path, especially when these requests bypass expected middleware protections. You can use network traffic inspection tools or web server logs to identify such suspicious requests. For example, using command-line tools like curl or wget, you can test your Traefik instance by sending requests with encoded characters in the path to see if middleware is bypassed. Example curl command: curl -v http://yourdomain.example.com/admin%2F - to check if the request bypasses middleware. Additionally, inspecting Traefik access logs or using tools like tcpdump or Wireshark to filter HTTP requests containing encoded characters in the URL path can help detect exploitation attempts. However, no specific detection commands are provided in the resources. [3]

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Compliance Impact

This vulnerability allows attackers to bypass security middleware and access restricted backend services, potentially leading to unauthorized access to sensitive data or protected internal functions. Such unauthorized access could result in violations of compliance requirements under standards like GDPR or HIPAA, which mandate strict access controls and protection of sensitive information. Therefore, if exploited, this vulnerability could negatively impact an organization's ability to comply with these regulations by exposing protected data or systems to unauthorized parties. [3]

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