{"id":"CVE-2026-113656","aliases":["GHSA-89mh-mm8c-mv7f"],"title":"ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS","summary":"ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS","severity":"medium","cvss":5.3,"cwe":["CWE-770"],"vendor":"apostrophecms","product":"@apostrophecms/form","ecosystem":"npm","affected":["@apostrophecms/form < 1.5.5"],"patched":["@apostrophecms/form 1.5.5"],"published":"2026-10-20","updated":"2026-10-20","sourceUpdated":"2026-10-20T18:08:32Z","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-89mh-mm8c-mv7f","references":[{"url":"https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-89mh-mm8c-mv7f"},{"url":"https://github.com/apostrophecms/apostrophe/commit/9500b8b0e1d630d5e07fbb5fd2c25ed0943845ce"},{"url":"https://github.com/apostrophecms/apostrophe/commit/f84fd41cbf6c22eb8d0008fc9c25df1f7130b350"},{"url":"https://github.com/apostrophecms/apostrophe/releases/tag/@apostrophecms/form@1.5.5"},{"url":"https://github.com/advisories/GHSA-89mh-mm8c-mv7f"}],"tags":["ghsa","npm","cve.org"],"ingestedAt":"2026-10-20T17:12:53.597Z","slug":"CVE-2026-113656","body":"## Overview\n\n**Summary**\nThe 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.\n\n**Details**\n`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.\n\n**PoC**\n```\n$ curl -s -c csrfjar.cookies http://localhost:3100/        # get vulnlab.csrf=csrf (any GET)\n$ df -P /tmp                                                # before: used=1105212\n$ curl -b csrfjar.cookies -X POST http://localhost:3100/api/v1/@apostrophecms/form/submit \\\n      -F \"file=@/tmp/opencode/big.bin;type=application/octet-stream\" &\n   DURING transfer:    used=1148668\n   still transferring: used=1226936        # +121MB mid-transfer on disk\n   http=500 time=1.78s sent=209715411B     # generic error AFTER full staging\n# Anonymous, zero credentials. 200MB written to /tmp pre-validation.\n```\n\n**Impact**\nAny 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 transfers risk orphaning staged files (no `req.aborted` cleanup).\n\n\n**Remediation** — Set multer `limits` (fileSize, fields, parts, fieldSize); perform auth/role/existence checks before the multer mount or inside the checked handler; unlink staged files on first read and on `req.aborted`/error; add per-IP rate limiting.\n\n## Affected packages\n\n- `@apostrophecms/form < 1.5.5`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `@apostrophecms/form 1.5.5`","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}