CVE-2026-4231: Vanna-AI Vanna SSRF Vulnerability

CVE-2026-4231 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in vanna-ai vanna up to version 2.0.2. This vulnerability affects the update_sql and run_sql functions within the file src/vanna/legacy/flask/__init__.py of the Endpoint component. An attacker can exploit this flaw remotely by manipulating requests to force the server to make unintended requests to internal or external resources.

Critical Impact

This SSRF vulnerability allows unauthenticated remote attackers to potentially access internal services, bypass firewall protections, and exfiltrate sensitive data from systems that should not be externally accessible.

Affected Products

• vanna-ai vanna versions up to and including 2.0.2
• Flask-based deployments using the legacy endpoint component
• Applications utilizing the update_sql or run_sql functions

Discovery Timeline

• 2026-03-16 - CVE-2026-4231 published to NVD
• 2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-4231

Vulnerability Analysis

This vulnerability is classified as CWE-918 (Server-Side Request Forgery), which occurs when the web application fetches a remote resource without sufficiently validating the user-supplied URL. In the context of vanna-ai vanna, the update_sql and run_sql functions in the legacy Flask endpoint fail to properly sanitize or restrict URLs provided by users. This allows attackers to craft malicious requests that cause the server to interact with arbitrary internal or external destinations.

The exploit has been publicly disclosed and proof-of-concept information is available. The vendor was contacted regarding this vulnerability but did not respond, leaving users without an official patch at this time.

Root Cause

The root cause lies in insufficient input validation within the update_sql and run_sql functions located in src/vanna/legacy/flask/__init__.py. These functions accept user-controlled input that is subsequently used to construct server-side requests without adequate validation of the target URL scheme, host, or port. This design flaw allows attackers to redirect requests to unintended destinations, including internal network resources, cloud metadata endpoints, or other sensitive services.

Attack Vector

The attack can be initiated remotely over the network without requiring authentication. An attacker sends a specially crafted request to the vulnerable endpoint, manipulating parameters processed by the update_sql or run_sql functions. The server then makes a request to an attacker-specified destination, potentially exposing internal services or sensitive data.

The vulnerability mechanism involves user input being passed directly to request-generating functions without proper URL validation. Attackers can leverage this to probe internal network infrastructure, access cloud instance metadata (such as AWS IMDSv1 endpoints), or interact with other services accessible from the server's network position. Technical details and proof-of-concept information are available in the GitHub Gist referenced in the disclosure.

Detection Methods for CVE-2026-4231

Indicators of Compromise

• Unusual outbound requests from the vanna application server to internal IP ranges (e.g., 169.254.169.254, 10.x.x.x, 192.168.x.x)
• Log entries showing requests to cloud metadata endpoints or other internal services that should not be accessed
• Anomalous traffic patterns from the Flask application to unexpected external domains

Detection Strategies

• Monitor network traffic from the vanna-ai application server for requests to internal IP addresses or cloud metadata services
• Implement logging on the update_sql and run_sql endpoint calls and analyze for suspicious URL patterns
• Deploy web application firewall (WAF) rules to detect and block SSRF attempt patterns in request parameters

Monitoring Recommendations

• Enable detailed request logging for the Flask application to capture all incoming parameters and outbound connections
• Configure alerting for any requests to RFC 1918 private address ranges or link-local addresses from the application
• Regularly review application logs for unusual endpoint access patterns or repeated failed connection attempts

How to Mitigate CVE-2026-4231

Immediate Actions Required

• Restrict network access from the vanna-ai application server to only required external services using firewall rules
• Implement URL validation and allowlisting in a reverse proxy or WAF in front of the vulnerable endpoints
• Consider disabling the legacy Flask endpoint if not required for operations
• Monitor the VulDB entry for updates and any vendor response

Patch Information

As of the last update on 2026-03-16, no official patch has been released by the vendor. The vendor was contacted during responsible disclosure but did not respond. Users should monitor the official vanna-ai repository and security channels for any future patches or updates addressing this vulnerability.

Workarounds

• Implement strict URL allowlisting at the application level to only permit requests to known, trusted destinations
• Deploy network segmentation to limit the server's ability to reach sensitive internal resources
• Use a reverse proxy with SSRF protection capabilities to filter malicious requests before they reach the application
• Block access to cloud metadata endpoints (169.254.169.254) from the application server via firewall rules

# Example iptables rules to block common SSRF targets from the application server
# Block access to AWS/cloud metadata endpoint
iptables -A OUTPUT -d 169.254.169.254 -j DROP

# Block access to internal network ranges (adjust as needed)
iptables -A OUTPUT -d 10.0.0.0/8 -p tcp --dport 80 -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -p tcp --dport 443 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -p tcp --dport 80 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -p tcp --dport 443 -j DROP