CVE-2026-54238 — LOW (3.1) — White Hats Nepal

Vulnerability 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.

CVSS Score

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

LOW

Availability

NONE

Related Weaknesses (CWE)

CWE-613

References

FAQ

What is CVE-2026-54238?

CVE-2026-54238 is a vulnerability with a CVSS score of 3.1 (LOW). 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 JSO...

How severe is CVE-2026-54238?

CVE-2026-54238 has been rated LOW with a CVSS base score of 3.1/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-54238?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.