Open Redirect and SSRF in Gradio via Unvalidated File Fetch

Compliance Impact

The provided information does not explicitly discuss the impact of CVE-2026-59806 on compliance with common standards and regulations such as GDPR or HIPAA.

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Executive Summary

CVE-2026-59806 is a security vulnerability in Gradio versions before 6.20.0 involving an open redirect and server-side request forgery (SSRF) via the /gradio_api/file= endpoint.

Attackers can supply unvalidated HTTP or HTTPS URLs to the file_fetch() function, causing the server to redirect users to arbitrary URLs or perform client-side SSRF.

This allows attackers to craft malicious responses that target internal endpoints, such as cloud metadata services, to steal sensitive credentials like EC2 IAM role credentials.

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Impact Analysis

This vulnerability can impact you by enabling attackers to redirect users to malicious websites, potentially facilitating phishing attacks.

Additionally, it can be exploited to perform client-side SSRF attacks that access internal cloud metadata services, allowing attackers to retrieve sensitive credentials such as AWS EC2 IAM role credentials.

Such credential theft can lead to unauthorized access to cloud resources and further compromise of your infrastructure.

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Detection Guidance

This vulnerability can be detected by testing the /gradio_api/file= endpoint for open redirect and SSRF behavior. One common method is to use curl commands to submit HTTP or HTTPS URLs as parameters and observe if the server redirects or fetches the URLs without validation.

• Use curl to test open redirect by sending a request like: curl -v "http://<target>/gradio_api/file=https://evil.com/phishing" and check if the server redirects to the supplied URL.
• Test for SSRF by attempting to access internal metadata services, for example: curl -v "http://<target>/gradio_api/file=http://169.254.169.254/latest/meta-data/" and observe if the server fetches or redirects to internal IPs.

Detection involves verifying if the endpoint improperly redirects or fetches unvalidated URLs, which can be confirmed by monitoring the server's response and network traffic.

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Mitigation Strategies

The immediate mitigation step is to upgrade Gradio to version 6.20.0 or later, where this vulnerability has been fixed by replacing the open redirect with a secure SSRF-safe streaming proxy.

• Upgrade Gradio to version 6.20.0 or newer.
• If upgrading is not immediately possible, restrict access to the /gradio_api/file= endpoint to trusted users or networks to reduce exposure.
• Implement network-level controls to block outgoing requests to internal metadata IP addresses (e.g., 169.254.169.254) from the Gradio server.

The fix in version 6.20.0 includes validating that URLs resolve to public IPs, blocking non-public hosts, pinning resolved IPs to prevent DNS rebinding, and streaming content server-side instead of redirecting, which collectively mitigate open redirect and SSRF risks.

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