CVE-2026-54238 Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-54238?
CVE-2026-54238 is a low-severity vulnerability in supabase realtime, published on 22 Oct 2026.
Official description
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.
Weakness: CWE-613
Which versions are affected by CVE-2026-54238?
How do I fix CVE-2026-54238?
No fix has been published for CVE-2026-54238 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-54238 being exploited?
There is no known exploitation of CVE-2026-54238 in the wild and no public exploit code.
Sources
Also known as GHSA-hg9h-6mhq-6c2v.