Open WebUI SSRF Bypass via Redirect Headers

Executive Summary

This vulnerability exists in Open WebUI versions before 0.6.27 and is a server-side request forgery (SSRF) issue in the /api/v1/retrieval/process/web endpoint.

Authenticated users can bypass SSRF protections by manipulating URL parameters with location redirect headers.

This allows attackers to access internal services and potentially execute commands using instance secrets.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability involves Server-Side Request Forgery (SSRF) via the /api/v1/retrieval/process/web endpoint, where authenticated users can manipulate URL parameters with location redirect headers to bypass SSRF protections.

To detect this vulnerability on your system or network, you can monitor and analyze HTTP requests to the /api/v1/retrieval/process/web endpoint for unusual or suspicious URL parameters that include redirects or location headers pointing to internal or unauthorized destinations.

Suggested commands to help detect exploitation attempts include:

• Using network traffic analysis tools like tcpdump or Wireshark to capture and filter HTTP requests to the vulnerable endpoint, e.g., `tcpdump -i any -A 'tcp port 80 or 443 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'` and then searching for `/api/v1/retrieval/process/web` in the payload.
• Using grep or similar tools on web server logs to find requests to the vulnerable endpoint with suspicious URL parameters, e.g., `grep '/api/v1/retrieval/process/web' /var/log/nginx/access.log | grep 'Location:'`.
• Checking for unexpected outbound requests or redirects from the server that might indicate SSRF exploitation, for example by monitoring logs or using tools like curl or wget to test the endpoint manually.

Useful 0 Not Useful 0

Impact Analysis

The vulnerability can allow an attacker with authentication to bypass SSRF protections and access internal services that are normally protected.

This could lead to unauthorized command execution via instance secrets, potentially compromising the affected system.

Useful 0 Not Useful 0

Compliance Impact

The provided context and resources do not contain specific information regarding the impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

Useful 0 Not Useful 0

Mitigation Strategies

The immediate mitigation step is to upgrade Open WebUI to version 0.6.27 or later, where the SSRF vulnerability has been patched.

If upgrading is not immediately possible, you should implement or verify the presence of SSRF protections such as the configurable blocklist mechanism introduced in the patch. This includes:

• Using domain and IP filtering to block access to sensitive internal metadata IP addresses and domains (e.g., 169.254.169.254, metadata.google.internal).
• Ensuring that URLs used in web fetch operations are validated to allow only HTTP or HTTPS schemes and filtered against the blocklist.
• Disabling local web fetch features if not required, to prevent requests to private IP addresses.

Monitoring and logging attempts to access the vulnerable endpoint and blocking suspicious requests can also help reduce risk until the patch is applied.

Useful 0 Not Useful 0