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CVE-2026-54238low3.1

Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization

Impact

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…

Source excerpt · GitHub_M

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

supabase · GitHub_M

realtime

1 range
GitHub_M version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

< 2.103.1

unaffected

unknown

Other versions: unknown

Original source 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.

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-54238

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cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-613 ↗

CWE-613: Insufficient Session Expiration

GitHub_M

Related →
Contributing organizations · 2
GitHub_M

Assigning organization

2026-10-22
CISA-ADP

Additional data publisher

2026-10-30

What changed

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References

4 sources
github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v
Security advisoryGitHub_M
github.com/supabase/realtime/pull/1934
PatchGitHub_M
github.com/supabase/realtime/commit/ac229d7eff2798b12b994e07bdd64f5e9b56374a
PatchGitHub_M
github.com/supabase/realtime/releases/tag/v2.103.1
Release notesGitHub_M