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CVE-2026-54238— Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization

Quick assessment

Affected
supabase realtime
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Supabase Realtime 通过 WebSocket 提供广播（Broadcast）、在线状态（Presence）和 PostgreSQL 变更（Postgres Changes）功能。在 2.103.1 版本之前，REST 广播端点在 JWT 的 （过期时间）声明被编码为 JSON 字符串而非 JSON 数字时，会接受已过期的令牌。而同一路由若使用相同的租户密钥签名、且 为整数时，则会正确拒绝已过期的令牌。被接受的请求会返回 202 状态码，并将广播消息发送给订阅者。此漏洞可能允许未认证的攻击者向订阅者广

CVSS 3.1 · Low

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
supabase realtime < 2.103.1 affected
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I. Basic Information for CVE-2026-54238

Vulnerability Information
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Vulnerability Title
Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
不充分的会话过期机制
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
supabase realtime < 2.103.1 -

II. Public POCs for CVE-2026-54238

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III. Intelligence Information for CVE-2026-54238

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Patches & Fixes for CVE-2026-54238 (2)

Vendor Advisories for CVE-2026-54238 (1)

Vendor Pages for CVE-2026-54238 (1)

IV. Related Vulnerabilities

Same product: realtime
Same vendor: supabase
Same weakness: CWE-613

V. Comments for CVE-2026-54238

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