{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "0.23.35"
              },
              {
                "introduced": "1.0.0-M1"
              },
              {
                "fixed": "1.0.0-M47"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "introduced": "756ce63aee681c5b632bbeafe0b8fde2f3d237f4"
            },
            {
              "fixed": "a83f5f4f7e14c5b4d4a91dd71b105cbbbb391298"
            },
            {
              "fixed": "6083780a3009bd7b26033b0ceb3d32c658b0377e"
            },
            {
              "fixed": "d578c3c9da6193627d40fa785e612cda7fcd77b3"
            }
          ],
          "repo": "https://github.com/http4s/http4s",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-jrxx-w2m8-5hf5"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-400",
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69209.json"
  },
  "details": "Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that completes a WebSocket handshake against an http4s-blaze-server or http4s-ember-server endpoint can exhaust server memory with oversized frames or fragmented messages. The patched decoder applies a configurable 64 MiB default limit to individual frames and defragmented messages through EmberServerBuilder.withMaxWebSocketMessageSize. This issue is fixed in versions 0.23.35 and 1.0.0-M47.",
  "id": "CVE-2026-69209",
  "modified": "2026-09-18T03:31:02.483428399Z",
  "published": "2026-09-15T18:55:29.782Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/http4s/http4s/releases/tag/v0.23.35"
    },
    {
      "type": "WEB",
      "url": "https://github.com/http4s/http4s/releases/tag/v1.0.0-M47"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69209.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/http4s/http4s/security/advisories/GHSA-jrxx-w2m8-5hf5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-69209"
    },
    {
      "type": "FIX",
      "url": "https://github.com/http4s/http4s/commit/d578c3c9da6193627d40fa785e612cda7fcd77b3"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Http4s: WebSocket decoder accepts unbounded message sizes"
}