CVE-2026-113658 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in apostrophe. A fix is available for apostrophe — see the affected versions and patch details below.
ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-113658.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-113658 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
apostropheReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A rejected upload can remain in the operating system temporary directory.
Multer writes the file before its extension is checked, and the rejection path does not remove that temporary file. An unauthenticated requester can repeat this with large files and steadily consume temporary disk space.
Details
The endpoint is:
POST /api/v1/@apostrophecms/rich-text-widget/generate-csv-table
In packages/apostrophe/modules/@apostrophecms/rich-text-widget/lib/apiRoutes.js, Multer first writes the upload to os.tmpdir(). The handler then rejects filenames whose extension is not csv, but there is no cleanup of the Multer file on this error path.
The route does not require an authenticated user. A normal CSRF cookie is sufficient.
During testing, the request returned HTTP 400 with Only csv files are supported, while the complete uploaded content remained in a randomly named file in the configured temporary directory after the response.
Relationship to prior public work
I reviewed PR #5013, which migrated the Rich Text CSV upload path from connect-multiparty to Multer. This report concerns cleanup after that migration: the rejected Multer file remains on disk, a behavior not described in the PR or its review discussion.
POC
Create a small test file. A larger file can be used to demonstrate disk growth, but 1 MiB is enough for a safe local reproduction:
dd if=/dev/zero of=rejected.txt bs=1M count=1
Obtain the normal site cookies and send the rejected upload:
curl -c cookies.txt 'http://127.0.0.1:3000/' > /dev/null
curl -i -b cookies.txt \
-F '[email protected];filename=rejected.txt;type=text/plain' \
'http://127.0.0.1:3000/api/v1/@apostrophecms/rich-text-widget/generate-csv-table'
The response is HTTP 400. Compare the contents of the system temporary directory before and after the request:
ls -lt /tmp
A new randomly named file remains present and contains the uploaded bytes.
No login is required. Repeating the multipart request creates additional persistent temporary files.
Impact
A remote unauthenticated attacker can fill the partition used by the operating system temporary directory. Once that partition is exhausted, Apostrophe and unrelated services on the same host may fail to upload files, create temporary data, or continue operating normally.
The attack requires only repeated HTTP requests and the stored files remain after each rejected response.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | apostrophe | all versions | 4.33.0npm install apostrophe@4.33.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for apostrophe, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update apostrophe to 4.33.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-113658 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-113658 in your dependencies?
Find it across npm, including transitive dependencies.