erlang-cowboy — security advisory

{
  "id": "d62949e21ef00dfbd28b8f4b8de55e628bd0fb0fc08321f682d0a983a82701e8",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-8466",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-8466",
    "summary": "Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows denial of service via unbounded buffer accumulation in multipart header parsing. cowboy_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) > 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. This issue affects cowboy from 2.0.0 before 2.15.0.",
    "evidence": "osv:DEBIAN-CVE-2026-8466",
    "products": [
      {
        "name": {
          "value": "erlang-cowboy",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.16.1+dfsg-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "0.10.0+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.6.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.6.1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.6.1-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.6.1-4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.8.6+dfsg-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.8.6+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.0.0+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.0.0~pre.1+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.0.0~pre.1+dfsg1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.0.0~pre.1+dfsg1-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.0.0~pre.1+dfsg1-4",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2026-8466",
      "aliases": [
        "DEBIAN-CVE-2026-8466"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.16.1+dfsg-1"
                }
              ]
            }
          ],
          "package": {
            "name": "erlang-cowboy",
            "purl": "pkg:deb/debian/erlang-cowboy?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "0.10.0+dfsg1-1",
            "0.6.1-1",
            "0.6.1-2",
            "0.6.1-3",
            "0.6.1-4",
            "0.8.6+dfsg-1",
            "0.8.6+dfsg1-1",
            "1.0.0+dfsg1-1",
            "2.0.0~pre.1+dfsg1-1",
            "2.0.0~pre.1+dfsg1-2",
            "2.0.0~pre.1+dfsg1-3",
            "2.0.0~pre.1+dfsg1-4"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-8466.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-27T09:47:29.667611196Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-8466"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-8466"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-8466",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 460959,
  "published_at": "2026-05-13T19:17:30.54+00:00"
}