ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS

{
  "id": "9ac67e71e11997f36bb1e975ba23f24994d887e1b00dc8a8ddf72f76d94de7e7",
  "url": "https://osv.dev/vulnerability/GHSA-89mh-mm8c-mv7f",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS",
    "summary": "**Summary** The form submission endpoint runs `multer({ dest: os.tmpdir() }).any()` before authentication, API-key, CSRF-equivalent, or form-existence logic, with no size/count/rate limits. Unauthenticated users can stream unbounded bodies to disk per request; cleanup occurs only after the full body is received. **Details** `packages/form/index.js` `apiRoutes.post.submit` (L274–296): `[ multer({ dest: os.tmpdir() }).any(), self.normalizeFiles, async function (req) { try { submitForm } finally { unlink files } } ]`. No `limits`, no rate limiting, no pre-validation. \"CSRF\" is a fixed-value double-submit cookie (`vulnlab.csrf=csrf`, set on any GET, express/index.js L694–703) — trivially obtainable anonymously. **PoC** ``` $ curl -s -c csrfjar.cookies http://localhost:3100/ # get vulnlab.csrf=csrf (any GET) $ df -P /tmp # before: used=1105212 $ curl -b csrfjar.cookies -X POST http://localhost:3100/api/v1/@apostrophecms/form/submit \\ -F \"file=@/tmp/opencode/big.bin;type=application/octet-stream\" & DURING transfer: used=1148668 still transferring: used=1226936 # +121MB mid-transfer on disk http=500 time=1.78s sent=209715411B # generic error AFTER full staging # Anonymous, zero credentials. 200MB written to /tmp pre-validation. ``` **Impact** Any unauthenticated client can force the server to persist entire request bodies to the temp filesystem and CPU-decode them; parallel requests exhaust disk `/tmp` (process/host crash) and saturate the event loop — a trivial remote DoS. Aborted ",
    "evidence": "osv:GHSA-89mh-mm8c-mv7f",
    "products": [
      {
        "name": {
          "value": "@apostrophecms/form",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.5.5",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-89mh-mm8c-mv7f",
      "aliases": [
        "CVE-2026-113656",
        "GHSA-89mh-mm8c-mv7f"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.5.5"
                }
              ]
            }
          ],
          "package": {
            "name": "@apostrophecms/form",
            "purl": "pkg:npm/%40apostrophecms/form",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-89mh-mm8c-mv7f/GHSA-89mh-mm8c-mv7f.json"
          }
        }
      ],
      "modified": "2026-10-20T18:15:04.526192205Z",
      "provider": "osv",
      "references": [
        "https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-89mh-mm8c-mv7f",
        "https://github.com/apostrophecms/apostrophe/commit/9500b8b0e1d630d5e07fbb5fd2c25ed0943845ce",
        "https://github.com/apostrophecms/apostrophe/commit/f84fd41cbf6c22eb8d0008fc9c25df1f7130b350",
        "https://github.com/apostrophecms/apostrophe",
        "https://github.com/apostrophecms/apostrophe/releases/tag/@apostrophecms/form@1.5.5"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-20T18:08:31Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-113656",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 390139,
  "published_at": "2026-10-20T18:08:31+00:00"
}