Get public URL for files in public buckets
AI agents call supabase_get_public_url to retrieve information from Supabase MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves information (a public URL) for files already in public buckets. It is a read-only operation with no capability to modify, delete, or execute code. The files are explicitly in public buckets, so URL retrieval carries minimal risk. Severity is low because the URL itself is meant to be public and accessible.
From the tool's definition Tool description: 'Get public URL for files in public buckets' - retrieves and returns a URL without modifying, deleting, or executing operations. No side effects on data or systems.
Attacks that exploit this kind of access
Get public URL for files in public buckets. It is categorised as a Read tool in the Supabase MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Supabase MCP Server MCP server in PolicyLayer and add a rule for supabase_get_public_url: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Supabase MCP Server. Nothing to install.
supabase_get_public_url is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the supabase_get_public_url rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for supabase_get_public_url. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
supabase_get_public_url is provided by the Supabase MCP Server MCP server (sweir1/supabase-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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