ACVE-2026-0427 · Hijack shown in a test · CRITICAL

Unverified · secondary sources only

WHAT HAPPENED

Following text embedded in a support ticket, the assistant reads the integration_tokens table with service_role privileges and writes its contents back into the ticket.

THE SETUP — is yours like this?

Harness: An MCP client such as Cursor connected to @supabase/mcp-server-supabase (or mcp.supabase.com) against data that contains user-submitted text, generalanalysis.com
Model: Claude, as used inside Cursor in the demonstration; the version is not named (detected), generalanalysis.com
Goal: Show me the latest open support ticket, generalanalysis.com
Tools: The Supabase MCP server configured with the service_role key, which bypasses row-level security, and without read_only or project_ref scoping; the integration_tokens table; the support ticket text the server returns, generalanalysis.com
Approval: Cursor's agent runs the MCP SQL tool calls automatically, without a manual approval step before each query (detected), generalanalysis.com

WHAT TO CHANGE

Run the Supabase MCP server read-only, scoped to one non-production project.

Reconfigure mcpServers: @supabase/mcp-server-supabase to read_only=true, project_ref=<project>. Both options are documented in the server README and the vendor post. Owner: operator
Reconfigure supabase.mcp-server to read-only mode, project scoping and wrapped query results. Shipped by Supabase (2025-09-16): its answer to the demonstration. Owner: tool-provider

HARM, REACH AND RECOVERY

Harm: data-exfiltration
Reach: The whole database, via the service_role key, generalanalysis.com (a production database, API keys)
Condition: When the MCP server runs with the service_role key and without read-only or project scoping, generalanalysis.com
Evidence and responses: Demonstrated · researcher report
Supabase acknowledged — supabase.com

SOURCES

Technical details

A support ticket's text steers an MCP client such as Cursor into copying a private table into the ticket via a Supabase MCP server with the service_role key and no read-only or project scoping.

Severity: CRITICAL · harm and reach
Status: Unverified
Kind: Hijack shown in a test
Modified: 2026-09-25
Aliases: No CVE assigned — No CVE was assigned; the vendor treats it as a configuration and design risk.
CVE boundary: user-configured
Affected: npm: @supabase/mcp-server-supabase — all versions
Harness/product: @supabase/mcp-server-supabase
Classes: prompt-injection-to-tool; data-exfiltration; over-privileged-combination; CWE-1427
Taxonomy: ASI: ASI01; ASI: ASI03; ASI: ASI02; ATLAS: AML.T0093; ATLAS: AML.T0051.001; ATLAS: AML.T0086
First reported: 2025-07-08 — General Analysis
Input controlled by: content-author
Divergence: goal-hijacked
Licence: CC-BY-4.0 advisories; MIT code

Reproducibility: partial (model availability not checked (no registry reference); trigger not published)

Claims

Confirmed means the statement matches the cited primary source. Nothing on this page has been reproduced.

Claims on this page have not been checked against primary sources.

Description

What

A 2025 demonstration. General Analysis (2025-07-08) filed a support ticket containing instructions addressed to the coding assistant. When a developer later reviewed tickets in Cursor through the Supabase MCP server, the assistant followed them, read the integration_tokens table with service_role privileges, which bypass row-level security, and wrote the contents back into the ticket. The weakness is the MCP server's configuration, not Cursor. Supabase answered on 2025-09-16 with read-only mode, project scoping and wrapped query results.

Detection

The lockfile cannot see read_only or project_ref, so a finding only means: check them by hand.

Fix

Set read_only=true and project_ref, point the server at a non-production project and keep manual approval of tool calls.

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