ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

ApostropheCMS is an open-source Node.js content management system. Prior to 1.5.5 of the ApostropheCMS Form add-on, its form submission route stages unbounded multipart uploads before form validation or authentication and lacks upload size, count, and rate limits. Repeated unauthenticated submissions can consume temporary disk storage and disrupt form handling or other host services. This issue is fixed in ApostropheCMS Form 1.5.5.

Source published

20 Oct 2026 16:49:36 UTC

Source modified

21 Oct 2026 15:53:31 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

ApostropheCMS is an open-source Node.js content management system. Prior to 1.5.5 of the ApostropheCMS Form add-on, its form submission route stages unbounded multipart uploads before form validation or authentication and lacks upload size, count, and rate limits. Repeated unauthenticated submissions can consume temporary disk storage and disrupt form handling or other host services. This issue is fixed in ApostropheCMS Form 1.5.5.

Source published

Oct 20, 2026, 4:49:36 PM (timezone not stated)

Source modified

Oct 21, 2026, 3:53:31 PM (timezone not stated)

Observed here

7 Nov 2026 04:34:18 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

ApostropheCMS is an open-source Node.js content management system. Prior to 1.5.5 of the ApostropheCMS Form add-on, its form submission route stages unbounded multipart uploads before form validation or authentication and lacks upload size, count, and rate limits. Repeated unauthenticated submissions can consume temporary disk storage and disrupt form handling or other host services. This issue is fixed in ApostropheCMS Form 1.5.5.

Source published

20 Oct 2026 17:17:36 UTC

Source modified

21 Oct 2026 16:17:24 UTC

Observed here

25 Oct 2026 05:17:18 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

**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.

Source published

20 Oct 2026 18:08:31 UTC

Source modified

20 Oct 2026 18:15:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Publisher rating · MODERATE