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Response snapshot Oct 26, 2026, 22:09 UTC

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VulnerabilityCVE-2026-113664

ApostropheCMS import-export tar guard misses './..' because it is a literal '../' substring test

The tar-extraction guard added to `@apostrophecms/import-export` for GHSA-mwxc-m426-3f78 is a literal substring test for `../`, and `./..` does not contain that substring. An entry named `./..` therefore passes the guard, `path.

Published Updated

At a glance

Exploited
Not known
Severity
5.3 Medium (CVSS 4.0)
Chance of exploitation
0.5% in the next 30 days
Sources
1 source

What to do

GitHub lists first patched versions: @apostrophecms/import-export: 3.7.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-97wv-p4xx-c7mg (opens a new tab)

What happened

### Summary

The tar-extraction guard added to `@apostrophecms/import-export` for GHSA-mwxc-m426-3f78 is a literal substring test for `../`, and `./..` does not contain that substring. An entry named `./..` therefore passes the guard, `path.join` normalizes it to the parent of the export directory, and the resulting `fs.WriteStream` opens a directory and emits `EISDIR` with no `error` listener attached, which terminates the Node process.

Confirmed on default-branch HEAD `1bd5d0a7a6fe880836fa75adad6964f1c577d640`, package version `3.6.2`.

### Details

Continue reading

`packages/import-export/lib/formats/gzip.js`, in the tar-stream `entry` handler inside `extract(filepath, exportPath)`:

```js const name = header.name.replace(/\\/g, '/'); if (name.includes('../')) { // skipped } ... stream.pipe(fs.WriteStream(path.join(exportPath, name))); ```

Two separate problems sit in those four lines. The guard tests the raw entry name for a substring instead of resolving the joined path and requiring containment, and the write stream has no `error` handler, so any stream error becomes an unhandled `'error'` event.

Reaching it needs an account that can import, nothing more. `packages/import-export/modules/@apostrophecms/import-export-page/index.js` exposes `post.importExportImport`, which calls into `lib/methods/import.js`; that handler requires `req.user` and then calls `format.input(exportPath)`, which for a `.gz` upload is `gzip.js` calling `extract()` on the uploaded archive.

### PoC

This is not an end-to-end exploit. What follows is each of the three primitives the crash depends on, executed individually, plus a source-level trace of the route. The chain from `post.importExportImport` to `extract()` was read, not observed.

The guard misses the payload:

```bash node -e "console.log('./..'.includes('../')); console.log('..'.includes('../')); console.log('a/./..'.includes('../'));" ```

```text false false false ```

`path.join` then resolves it out of the export directory:

```bash node -e "const path=require('path'); const exportPath='/tmp/exportRoot'; console.log(path.join(exportPath,'./..'));" ```

```text /tmp ```

And a write stream opened on a directory, with no `error` listener, kills the process rather than failing the request:

```bash node -e "const fs=require('fs'); const s=fs.createWriteStream('/tmp'); s.write('x'); s.end(); setTimeout(()=>console.log('still alive'),500);" ```

```text events.js:291 throw er; // Unhandled 'error' event ^

Error: EISDIR: illegal operation on a directory, open '/tmp' Emitted 'error' event on WriteStream instance at: at internal/fs/streams.js:361:12 at FSReqCallback.oncomplete (fs.js:156:23) { errno: -21, code: 'EISDIR', syscall: 'open', path: '/tmp' } ```

The `events.js:291` frame shows that transcript came off the Node 14 line my audit box had. The unhandled-`error`-event behavior is not version specific, but the exact message on your supported Node versions is worth a re-run.

Source-side confirmation without running anything:

```bash grep -n "includes('../')" packages/import-export/lib/formats/gzip.js grep -n "WriteStream" packages/import-export/lib/formats/gzip.js ```

### Impact

An authenticated user who can reach the import UI uploads one crafted archive and takes down the Node process handling it. Every worker that picks up such an archive dies the same way.

### Suggested fix

Resolve the target and require containment, and attach an error handler:

```js const base = path.resolve(exportPath); const target = path.resolve(path.join(exportPath, name));

if (target !== base && !target.startsWith(base + path.sep)) { stream.on('end', next); stream.resume(); return; }

if (header.type === 'directory') { fsp.mkdir(target).then(next).catch(reject); } else { const out = fs.WriteStream(target); out.on('error', reject); stream.pipe(out); stream.on('end', next); } ```

The error handler earns its place independently. Any tar entry that lands on an existing directory name has the same effect whether or not traversal is involved.

### Why this is not GHSA-mwxc-m426-3f78

The `name.includes('../')` check is the mitigation shipped for GHSA-mwxc-m426-3f78 / CVE-2026-32731. It stops names carrying the literal `../` sequence. It does not canonicalize the joined path, so `./..` and a bare `..` still get through, and it did not touch the missing `error` listener. This report is about what the substring test leaves behind.

AI assistance was used for the code audit and drafting. The exact guard and `WriteStream` lines in `packages/import-export/lib/formats/gzip.js` at the stated HEAD were manually verified, the import route from the page module through `lib/methods/import.js` into the entry handler were manually traced, and the three Node one-liners were manually ran and copied verbatim.

Affected package ranges reported by GitHub: @apostrophecms/import-export: < 3.7.0

Scores and how they were measured

CVSS base severity

5.3

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

Measurement source (opens a new tab)

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

EPSS probability

0.5%

Scored Percentile 41.5%

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-97wv-p4xx-c7mg (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-97wv-p4xx-c7mg, 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-97wv-p4xx-c7mg, 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-97wv-p4xx-c7mg, 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-97wv-p4xx-c7mg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-97wv-p4xx-c7mg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-97wv-p4xx-c7mg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-97wv-p4xx-c7mg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-97wv-p4xx-c7mg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-97wv-p4xx-c7mg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-113664, 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 20). ApostropheCMS import-export tar guard misses './..' because it is a literal '../' substring test (CVE-2026-113664). https://kevwire.com/record/CVE-2026-113664

MLA

"ApostropheCMS import-export tar guard misses './..' because it is a literal '../' substring test (CVE-2026-113664)." KEVWire, 20 Oct. 2026, kevwire.com/record/CVE-2026-113664.

Chicago

KEVWire. "ApostropheCMS import-export tar guard misses './..' because it is a literal '../' substring test (CVE-2026-113664)." Last modified October 20, 2026. https://kevwire.com/record/CVE-2026-113664.

Evidence summary (plain text)

ApostropheCMS import-export tar guard misses './..' because it is a literal '../' substring test (Oct 20, 2026).
The tar-extraction guard added to `@apostrophecms/import-export` for GHSA-mwxc-m426-3f78 is a literal substring test for `../`, and `./..` does not contain that substring. An entry named `./..` therefore passes the guard, `path.join` normalizes it to the parent of the export directory, and the resulting `fs.WriteStream` opens a directory and emits `EISDIR` with no `error` listener attached, which terminates the Node process.

Confirmed on default-branch HEAD `1bd5d0a7a6fe880836fa75adad6964f1c577d640`, package version `3.6.2`.
CVSS 5.3 (version 4.0; evidence as of Oct 20, 2026; https://github.com/advisories/GHSA-97wv-p4xx-c7mg).
EPSS 0.5% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-113664&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-97wv-p4xx-c7mg: https://github.com/advisories/GHSA-97wv-p4xx-c7mg
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNDowNjoxNFrOAAfxZw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
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
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-113664&date=2026-10-26
Record ID: CVE-2026-113664.
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 26, 2026, 19:40 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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