Live › vulnerability › CVE-2026-54238
Go to dashboardSupabase Realtime's REST broadcast endpoints accept an expired JWT when its exp claim is encoded as a JSON string rather than a number. An attacker holding such a token can push broadcast messages to subscribers of a project.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Projects running Supabase Realtime before version 2.103.1 that use the REST broadcast endpoints. The sources do not say whether managed Supabase hosting has already applied the patch, so self-hosted deployments are the clearest case. Applications that do not use broadcast messages are less exposed.
No product ranges from the sources yet.
2.103.12.103.1 or laterEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
Supabase Realtime provides Broadcast, Presence, and Postgres Changes via WebSockets. Prior to version 2.103.1, the REST broadcast endpoints accept an expired JWT when the exp claim is encoded as a JSON string instead of a JSON number. The same route rejects an expired integer exp token signed with the same tenant secret. The accepted request returns 202 and emits the broadcast to subscribers. This could allow an unauthenticated attacker can broadcast realtime messages to subscribers. The attack can be performed via the Internet/only from within the supabase project. The impact of broadcasting messages to subscribers is application specific. This issue has been patched in version 2.103.1.
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