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Response snapshot Oct 27, 2026, 04:12 UTC

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VulnerabilityCVE-2026-113658

ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory

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.

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.6% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: apostrophe: 4.33.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-qhcq-9pm2-c9w9 (opens a new tab)

What happened

### 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

Continue reading

The endpoint is:

```text 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](https://github.com/apostrophecms/apostrophe/pull/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:

```bash dd if=/dev/zero of=rejected.txt bs=1M count=1 ```

Obtain the normal site cookies and send the rejected upload:

```bash curl -c cookies.txt 'http://127.0.0.1:3000/' > /dev/null

curl -i -b cookies.txt \ -F 'file=@rejected.txt;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:

```bash 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 package ranges reported by GitHub: apostrophe: < 4.33.0

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.6%

Scored Percentile 49.2%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-qhcq-9pm2-c9w9 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qhcq-9pm2-c9w9, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qhcq-9pm2-c9w9, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qhcq-9pm2-c9w9, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qhcq-9pm2-c9w9, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    NVD CVE-2026-113658 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  7. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  8. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-113658, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 23). ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory (CVE-2026-113658). https://kevwire.com/record/CVE-2026-113658

MLA

"ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory (CVE-2026-113658)." KEVWire, 23 Oct. 2026, kevwire.com/record/CVE-2026-113658.

Chicago

KEVWire. "ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory (CVE-2026-113658)." Last modified October 23, 2026. https://kevwire.com/record/CVE-2026-113658.

Evidence summary (plain text)

ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory (Oct 20, 2026).
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.
CVSS 7.5 (version 3.1; evidence as of Oct 23, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-113658).
EPSS 0.6% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-113658&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-qhcq-9pm2-c9w9: https://github.com/advisories/GHSA-qhcq-9pm2-c9w9
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
NVD CVE-2026-113658: https://nvd.nist.gov/vuln/detail/CVE-2026-113658
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=6000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-113658&date=2026-10-26
Record ID: CVE-2026-113658.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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