CVE-2026-54238 (GCVE-0-2026-54238)

Vulnerability from cvelistv5 – Published: 2026-10-22 17:22 – Updated: 2026-10-22 17:22
VLAI
Title
Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization
Summary
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.
Severity
3.1 (Low)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
CWE
  • CWE-613 - Insufficient Session Expiration
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7815 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
supabase realtime Affected: < 2.103.1
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
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      "affected": [
        {
          "product": "realtime",
          "vendor": "supabase",
          "versions": [
            {
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          "value": "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."
        }
      ],
      "metrics": [
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              "type": "CWE"
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-22T17:22:50.862Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v",
          "tags": [
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          ],
          "url": "https://github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v"
        },
        {
          "name": "https://github.com/supabase/realtime/pull/1934",
          "tags": [
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          "url": "https://github.com/supabase/realtime/pull/1934"
        },
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          "tags": [
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          "url": "https://github.com/supabase/realtime/commit/ac229d7eff2798b12b994e07bdd64f5e9b56374a"
        },
        {
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          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/supabase/realtime/releases/tag/v2.103.1"
        }
      ],
      "source": {
        "advisory": "GHSA-hg9h-6mhq-6c2v",
        "discovery": "UNKNOWN"
      },
      "title": "Supabase Realtime: Expired JWTs with string exp are accepted by REST broadcast authorization"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-54238",
    "datePublished": "2026-10-22T17:22:50.862Z",
    "dateReserved": "2026-06-12T16:25:43.084Z",
    "dateUpdated": "2026-10-22T17:22:50.862Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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    "epss": {
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      "date": "2026-10-27",
      "epss": "0.00206",
      "percentile": "0.10655"
    },
    "nvd": {
      "cve": {
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                "product": "realtime",
                "vendor": "supabase",
                "versions": [
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                    "version": "\u003c 2.103.1"
                  }
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            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "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."
          }
        ],
        "id": "CVE-2026-54238",
        "lastModified": "2026-10-23T19:42:24.553",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
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                "confidentialityImpact": "NONE",
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            }
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        "published": "2026-10-22T18:17:28.993",
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            "source": "security-advisories@github.com",
            "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"
          },
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            "url": "https://github.com/supabase/realtime/security/advisories/GHSA-hg9h-6mhq-6c2v"
          }
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        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
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              {
                "lang": "en",
                "value": "CWE-613"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
        ]
      }
    }
  }
}



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