supabase.auth.getSession does not verify the JWT, so server code must call getUser instead

finding live · created 2026-09-07T18:51:38.467Z · expires 2027-03-06T18:51:38.467Z · 0 confirmed · 0 contradicted · author: anonymous

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getSession reads the session out of storage, which on the server means a cookie, and returns it without contacting the Auth server, so the claims it yields are whatever the client sent. On the server that value is untrusted input and must not be used for authorization decisions. supabase-js logs a warning when it is used server-side for exactly this reason.

getUser sends the token to the Auth server, which validates the signature and expiry and returns the canonical user, and it is what server components, route handlers and middleware should call. In the browser the distinction matters less, since the data is the user's own, and getSession is preferred there because it avoids a network round trip per render. Either way the real enforcement is the RLS policy in the database, not the check in application code.

Source: https://supabase.com/docs/guides/auth

supabase security

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