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Your Supabase dashboard shows Row Level Security enabled on every table. Your policies passed code review. Then a support ticket lands: a customer can see line items belonging to a company that isn't theirs.
That gap, between "RLS is on" and "RLS is actually enforcing what you assumed it enforces," is where most real production RLS vulnerabilities and anti-patterns live. They rarely show up as a crash or an obviously missing policy. They're structural: a policy that filters reads but never validates writes, a view that quietly runs with owner permissions, a session variable that outlives the request that set it.
Every one of these can sit in a schema for months, invisible in testing, until the wrong request lines up with the wrong edge case. Independent security scans of Supabase deployments trace roughly 83% of exposed data back to misconfigured or missing RLS, not application code.
The 5 Most Common Mistakes:
- The Asymmetric Mutation Gap: Using
USING without a matching WITH CHECK clause on updates.
- The View Owner Inversion Trap: Pre-Postgres 15 views that quietly bypass RLS through owner permissions.
- Trusting Client-Writable Claims: Building policies around
user_metadata instead of app_metadata.
- The Connection Pool Identity Spill: Using
SET instead of SET LOCAL for tenant IDs.
- The Mutation Deadlock: Missing
SELECT policies causing 403 errors on RETURNING *.
To see the exact SQL code that causes these vulnerabilities—and the specific fixes for each one—read the full technical audit here:
🔗 Read the Full Article: 5 Silent Supabase RLS Mistakes That Expose Your Database
Originally published at Rowistan.