{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "2.0.0"
              },
              {
                "fixed": "2.15.0"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "d3f15cfd8b2bb4c0c697bd995dfa4546474235ad"
            },
            {
              "fixed": "3b9fb5214d70f1c4707a095c4193214bc12a7c36"
            },
            {
              "fixed": "5c6a2061b41bb5771c4659fac7d5a822dca5bafb"
            }
          ],
          "repo": "https://github.com/ninenines/cowboy",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8466.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "917cf99e10c41676183d501b86af6e47c95afb89"
          },
          {
            "fixed": "5c6a2061b41bb5771c4659fac7d5a822dca5bafb"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows denial of service via unbounded buffer accumulation in multipart header parsing.\n\ncowboy_req:read_part/3 in src/cowboy_req.erl accumulates incoming request bytes into a Buffer binary with no upper-bound check. When cow_multipart:parse_headers/2 returns more or {more, Buffer2}, the function reads up to Length bytes (default 64 KB) from the request body and recurses with the enlarged buffer. There is no equivalent of the byte_size(Acc) \u003e Length guard present in the sibling function read_part_body/4. An unauthenticated attacker can send a multipart/form-data request whose body never yields a complete header section — for example, a body that never contains the advertised boundary delimiter, or one whose header lines never contain \\r\\n\\r\\n — and force the server process to accumulate memory linearly with the bytes the protocol layer is willing to deliver. A handful of concurrent such uploads is sufficient to exhaust BEAM memory.\n\nThis issue affects cowboy from 2.0.0 before 2.15.0.",
  "id": "CVE-2026-8466",
  "modified": "2026-07-08T05:37:03.256354654Z",
  "published": "2026-05-13T18:26:21.089Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-8466"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://cna.erlef.org/cves/CVE-2026-8466.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8466.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-8466"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ninenines/cowboy/commit/5c6a2061b41bb5771c4659fac7d5a822dca5bafb"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ninenines/cowboy"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Unbounded buffer accumulation in multipart header parsing causes denial of service in cowboy"
}