CVE-2026-54238
lowSupabase Realtime provides Broadcast, Presence, and Postgres Changes via WebSockets.
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/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/supabase/realtime/commit/ac229d7eff2798b12b994e07bdd64f5e9b56374a security-advisories@github.com
- https://github.com/supabase/realtime/pull/1934 security-advisories@github.com
- https://github.com/supabase/realtime/releases/tag/v2.103.1 security-advisories@github.com
- https://github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v security-advisories@github.com