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Medium, CVSS 5.3amended

ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS

CVE-2026-113656GHSA-89mh-mm8c-mv7f

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (@apostrophecms/form 1.5.5), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS
  • CVE-2026-113656: 0.46% estimated exploitation activity in the next 30 days; percentile 40.10 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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 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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-89mh-mm8c-mv7f

  2. Revision 2 · amended ·

    Amended from osv record GHSA-89mh-mm8c-mv7f

  3. Revision 1 · created ·

    Published from ghsa record GHSA-89mh-mm8c-mv7f

Agent brief

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# Patch Next advisory brief: CVE-2026-113656

Advisory: ApostropheCMS: Unauthenticated unbounded multipart upload → disk-exhaustion DoS
IDs: CVE-2026-113656, GHSA-89mh-mm8c-mv7f
Record: https://patchnext.com/advisories/cve-2026-113656 (revision 3, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @apostrophecms/form 1.5.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @apostrophecms/form: affected < 1.5.5; fixed in 1.5.5

## Suggested inspection (read-only)
- `npm ls @apostrophecms/form --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @apostrophecms/form.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-89mh-mm8c-mv7f (GitHub-reviewed advisory GHSA-89mh-mm8c-mv7f lists affected ranges: npm @apostrophecms/form >=0 <1.5.5)
- Verified: https://osv.dev/vulnerability/GHSA-89mh-mm8c-mv7f (OSV record GHSA-89mh-mm8c-mv7f lists affected ranges: npm @apostrophecms/form >=0 <1.5.5 (fixed))

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