---
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'
---

## Overview

**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 transfers risk orphaning staged files (no `req.aborted` cleanup).


**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.

## Affected packages

- `@apostrophecms/form < 1.5.5`

## Remediation

Upgrade to a patched release:

- `@apostrophecms/form 1.5.5`