CVE-2026-54238
CVE-2026-54238 · Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 3.1 · Low · EPSS 0.2%
- Published
- Updated
Affected products and versions
realtime
- Versions
- < 2.103.1: Affected
No fix published
Original sources
- https://github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v
- https://github.com/supabase/realtime/pull/1934
- https://github.com/supabase/realtime/commit/ac229d7eff2798b12b994e07bdd64f5e9b56374a
- https://github.com/supabase/realtime/releases/tag/v2.103.1
- https://nvd.nist.gov/vuln/detail/CVE-2026-54238