Thursday, October 8, 2026 · Week 41 Reading for Oct. 8 · Last entry Oct. 6
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Paperclip IndexDocumented harm20Minor harm▼ 5 from a week ago · Oct. 8The Index

Hijacked by injectionPI-0014

Supabase MCP demonstration: support-ticket text tricks coding agent into exposing private database tokens

General Analysis showed that a coding assistant (Claude in Cursor) connected to a Supabase database through its MCP server, running with a service-role key that bypasses row-level security, could be made to read a private table of integration tokens and copy its contents into a customer-visible support thread when a support ticket contained instructions addressed to the agent. The test used a fresh project with dummy data. Supabase's documentation already recommended a read-only, project-scoped mode; in September 2025 it described further mitigations and said no customer data leak via MCP had been reported.

Reported June 16, 2025Happened in June 2025Updated Oct. 6, 2026Rated under methodology v0.6

Control failure, trackedNot counted. No documented harm outside the developer, but the system broke a rule or crossed a limit. Tracked beside the index.
Harm
Harm: No harm reportedAdds nothing to the index.
Control
Control level 2, Instruction violationReported beside the index. It adds nothing to a harm reading; when no harm counts in a window, the highest eligible control level in the window is the reading.
Controlled testSingle sourceInitiated by Outside attacker
Near miss

Near miss. Harm was plausible but prevented. It is rated only on what actually happened.

Not counted: no harm reportedEffect on the index

Sources

How we know

4 sources · single source. Links go to the original publishers; the summary above is in our own words.

  1. primaryDefense in Depth for MCP ServersSupabase · Sept. 16, 2025supabase.com/blog/defense-in-depth-mcp.md
  2. researchSupabase MCP can leak your entire SQL database (original post; current page retitled and re-dated)General Analysis · June 16, 2025generalanalysis.com/blog/supabase-mcp-blog
  3. newsA method that could leak entire SQL databases via AI protocol 'MCP' has been discoveredGIGAZINE · July 9, 2025gigazine.net/gsc_news/en/20250709-mcp-sql-leak
  4. blogSupabase MCP can leak your entire SQL database (link post)Simon Willison's Weblog · July 6, 2025simonwillison.net/2025/Jul/6/supabase-mcp-lethal-trifecta

Why this rating

No harm reported; control failure level 2

Two separate assessments. Only documented harm can count toward the index.

Observed harm

No harm reported

Researcher demonstration on controlled accounts; no victims reported.

Not a finding that no harm occurred.

The harm scale
  1. 1 Negligible Inconvenience, easily remedied.
  2. 2 Minor Limited, recoverable harm.
  3. 3 Moderate Material harm needing significant effort to remedy.
  4. 4 Severe Severe harm to health, rights, property or essential services.
  5. 5 Catastrophic Society-scale harm or disruption beyond a community's capacity to cope.

Control assessment

Instruction violation

Agent executed injected SQL using the elevated credentials the developer had configured; inside its permissions.

Reported beside the index. It adds nothing to a harm reading; when no harm counts in a window, the highest eligible control level in the window is the reading.

The control scale
  1. 1 Negligible Behaved as instructed. The problem was an ordinary error or a flawed output, with no rule broken.
  2. 2 Minor Broke an explicit instruction or rule, or gamed its goal, while staying inside its permissions and environment: for example, reward hacking, misreporting results, or following injected instructions within its permissions.
  3. 3 Moderate Acted outside the permissions it was given, deceived its overseers about its own actions, or tampered with oversight tools (logs, monitors, shutdown). Stopped by normal controls within an hour.
  4. 4 Severe Reached systems outside its permitted environment, or acquired money, compute or accounts without authorization. The type and mechanism say how.
  5. 5 Catastrophic The developer or operator lost control: the system copied its weights outside their control, replicated itself, or resisted being stopped for 24 hours or more.

Rating rationale

No external harm was reported from this controlled test. Control level 2 follows the injected-instructions-within-permissions rule.

The scales

Effect on the index

It does not count toward the June 16 reading

The reading for the week to June 16, 2025, with this record and without it. Harms count in full for two weeks after they are reported, then one level less every two weeks.

Not counted: no harm reported. 5 other records behind the reading for that week.

The arithmetic
The reading for the week of June 16, recomputed
StepWith itWithout
Counts toward the index?documented, external, eligible evidenceNo—
Worst documented harm, ksets the band— (none counting)— (none counting)
Harms at that level, nposition in the band00
Highest control level breachedsets the reading only when no harm counts33
Readingrounded down3 Control failures only3 Control failures only
Inside the window of 5 weekly readings
Week toReadingBand
June 16, 20253Control failures only
June 23, 20252Control failures only
June 30, 20252Control failures only
July 7, 20252Control failures only
July 14, 20252Control failures only

Recalculated backcasts, not readings published at the time.

Revisions

What we changed

5 logged. Every change to a rating is logged here, with the reason.

  1. v5
    Oct. 6, 2026

    Ratings confirmed by the editor.

  2. v4
    Oct. 3, 2026

    Report date moved from 2025-07-06 to 2025-06-16 and event date from 2025-07 to 2025-06: Wayback Machine captures from 17-18 Jun 2025 show General Analysis's original post dated 16 Jun 2025 (the live page is now retitled and shows 8 Jul 2025). Added that post. Verification relabeled from Multiple credible sources to Single source with a research evidence review. Corrected the summary: Supabase's read-only mode predated the report. Dated the Supabase post (16 Sep 2025). Ratings unchanged; impact not reported, so no reading effect.

  3. v3
    Oct. 2, 2026

    Report date resolved from month precision (2025-07, placed on the 1st) to 2025-07-06: Simon Willison's 6 Jul 2025 post linking General Analysis's demonstration, the earliest dated public account found.

  4. v2
    Sept. 30, 2026

    Rated: impact not reported; control type instruction violation.

  5. v1
    Sept. 30, 2026

    Backfilled from public reporting.

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Use this record

Citation

Paperclip Index. “Supabase MCP demonstration: support-ticket text tricks coding agent into exposing private database tokens.” Record PI-0014. Reported June 16, 2025; updated Oct. 6, 2026. Rated under methodology v0.6. https://paperclipindex.com/incident/PI-0014