{"id":"CVE-2026-54238","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-54238","generatedAt":"2026-10-28T03:30:31.406Z","title":"This could allow an unauthenticated attacker can broadcast realtime messages to subscribers.","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.","published":"2026-10-22T18:17:29.000Z","lastModified":"2026-10-23T19:42:25.000Z","status":"Awaiting Analysis","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":3.1,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N"},"cwe":["CWE-613"],"affected":[],"epss":{"score":0.00206,"percentile":0.10639,"date":"2026-10-26","history":[{"date":"2026-10-23","score":0.00206,"percentile":0.10198}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.21%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-22T18:17:29.000Z","detail":{"score":"3.1","severity":"LOW","publishedAt":"2026-10-22T18:17:28.993Z"},"summary":"New CVE, low severity (CVSS 3.1)."}],"references":[{"url":"https://github.com/supabase/realtime/commit/ac229d7eff2798b12b994e07bdd64f5e9b56374a","source":"security-advisories@github.com"},{"url":"https://github.com/supabase/realtime/pull/1934","source":"security-advisories@github.com"},{"url":"https://github.com/supabase/realtime/releases/tag/v2.103.1","source":"security-advisories@github.com"},{"url":"https://github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v","source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-54238","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}